diff --git a/src/CMakeLists.txt b/src/CMakeLists.txt
index 8851182..f6f841a 100644
--- a/src/CMakeLists.txt
+++ b/src/CMakeLists.txt
@@ -17,6 +17,7 @@ add_executable(sysyc
   SysYIRGenerator.cpp
   # Backend.cpp
   SysYIRPrinter.cpp
+  SysYIROptPre.cpp
   RISCv32Backend.cpp
 )
 target_include_directories(sysyc PRIVATE ${CMAKE_CURRENT_BINARY_DIR} ${CMAKE_CURRENT_SOURCE_DIR}/include)
diff --git a/src/SysYIROptPre.cpp b/src/SysYIROptPre.cpp
index edd9333..90ff3fd 100644
--- a/src/SysYIROptPre.cpp
+++ b/src/SysYIROptPre.cpp
@@ -38,9 +38,8 @@ void SysYOptPre::SysYDelInstAfterBr() {
     for (auto &basicBlock : basicBlocks) {
       bool Branch = false;
       auto &instructions = basicBlock->getInstructions();
-      auto iter = instructions.begin();
       auto Branchiter = instructions.end();
-      for (auto iter = instructions->begin(); iter != instructions->end();iter++) {
+      for (auto iter = instructions.begin(); iter != instructions.end(); ++iter) {
         if (Branch) 
           usedelete(iter->get());
         else if ((*iter)->isTerminator()){
@@ -48,8 +47,8 @@ void SysYOptPre::SysYDelInstAfterBr() {
           Branchiter = iter;
         }
       }
-      Branchiter++;
-      while(Branchiter != instructions->begin()) 
+      if (Branchiter != instructions.end()) ++Branchiter;
+      while (Branchiter != instructions.end()) 
         Branchiter = instructions.erase(Branchiter);
       
       if (Branch) {  // 更新前驱后继关系
@@ -183,10 +182,8 @@ void SysYOptPre::SysYDelNoPreBLock() {
     }
 
     
-    for (auto blockIter = func->getBasicBlocks().begin(); blockIter != func->getBasicBlocks().end();blockIter++) {
+    for (auto blockIter = func->getBasicBlocks().begin(); blockIter != func->getBasicBlocks().end();) {
       if (!blockIter->get()->getreachable()) {
-        //// 处理phi指令
-        // 删除不可达基本块的phi指令的操作数
         for (auto succblock : blockIter->get()->getSuccessors()) {
           int indexphi = 1;
           for (auto pred : succblock->getPredecessors()) {
@@ -202,14 +199,16 @@ void SysYOptPre::SysYDelNoPreBLock() {
             phiinst->removeOperand(indexphi);
           }
         }
-        // 删除不可达基本块
-        func->removeBasicBlock(blockIter->get());
+        // 删除不可达基本块，注意迭代器不可达问题
+        func->removeBasicBlock((blockIter++)->get());
+      } else {
+        blockIter++;
       }
     }
   }
 }
 
-void SysyOptimization::SysyDelEmptyBlock() {
+void SysYOptPre::SysYDelEmptyBlock() {
   auto &functions = pModule->getFunctions();
   for (auto &function : functions) {
     // 收集不可达基本块
@@ -259,7 +258,7 @@ void SysyOptimization::SysyDelEmptyBlock() {
       --thelastinst;
 
       // 根据br指令传递的后继块信息，跳过空块链
-      if (thelastinst->get()->getKind()->isUnconditional()) {
+      if (thelastinst->get()->isUnconditional()) {
         BasicBlock* OldBrBlock = dynamic_cast<BasicBlock *>(thelastinst->get()->getOperand(0));
         BasicBlock *thelastBlockOld = nullptr;
         // 如果空块链表为多个块
@@ -285,7 +284,7 @@ void SysyOptimization::SysyDelEmptyBlock() {
 
           // 更新phi指令的操作数
           // 移除thelastBlockOld对应的phi操作数
-          for (auto &InstInNew : dynamic_cast<BasicBlock *>(thelastinst->get()->getOperand(1))->getInstructions()) {
+          for (auto &InstInNew : dynamic_cast<BasicBlock *>(thelastinst->get()->getOperand(0))->getInstructions()) {
             if (InstInNew->isPhi()) {
               dynamic_cast<PhiInst *>(InstInNew.get())->removeOperand(indexphi + 1);
             } else {
@@ -322,12 +321,12 @@ void SysyOptimization::SysyDelEmptyBlock() {
         // auto indexInNew = dynamic_cast<BasicBlock *>(thelastinst->get()->getOperand(0))->getPredecessors().
 
         if (thelastBlockOld != nullptr) {
-          int index = 0;
+          int indexphi = 0;
           for (auto &pred : dynamic_cast<BasicBlock *>(thelastinst->get()->getOperand(1))->getPredecessors()) {
             if (pred == thelastBlockOld) {
               break;
             }
-            index++;
+            indexphi++;
           }
 
           for (auto &InstInNew : dynamic_cast<BasicBlock *>(thelastinst->get()->getOperand(1))->getInstructions()) {
@@ -362,12 +361,12 @@ void SysyOptimization::SysyDelEmptyBlock() {
         dynamic_cast<BasicBlock *>(thelastinst->get()->getOperand(2))->addPredecessor(basicBlock.get());
 
         if (thelastBlockOld != nullptr) {
-          int index = 0;
+          int indexphi = 0;
           for (auto &pred : dynamic_cast<BasicBlock *>(thelastinst->get()->getOperand(2))->getPredecessors()) {
             if (pred == thelastBlockOld) {
               break;
             }
-            index++;
+            indexphi++;
           }
           for (auto &InstInNew : dynamic_cast<BasicBlock *>(thelastinst->get()->getOperand(2))->getInstructions()) {
             if (InstInNew->isPhi()) {
@@ -398,12 +397,12 @@ void SysyOptimization::SysyDelEmptyBlock() {
           basicBlock->addSuccessor(dynamic_cast<BasicBlock *>(thelastinst->get()->getOperand(0)));
           dynamic_cast<BasicBlock *>(thelastinst->get()->getOperand(0))->addPredecessor(basicBlock.get());
           if (thelastBlockOld != nullptr) {
-            int index = 0;
+            int indexphi = 0;
             for (auto &pred : dynamic_cast<BasicBlock *>(thelastinst->get()->getOperand(0))->getPredecessors()) {
               if (pred == thelastBlockOld) {
                 break;
               }
-              index++;
+              indexphi++;
             }
 
             for (auto &InstInNew : dynamic_cast<BasicBlock *>(thelastinst->get()->getOperand(0))->getInstructions()) {
@@ -461,7 +460,7 @@ void SysYOptPre::SysYAddReturn() {
   auto &functions = pModule->getFunctions();
   for (auto &function : functions) {
     auto &func = function.second;
-    auto &basicBlocks = func->getBasicBlocks();
+    auto basicBlocks = func->getBasicBlocks();
     for (auto &block : basicBlocks) {
       if (block->getNumSuccessors() == 0) {
         // 如果基本块没有后继块，则添加一个返回指令
diff --git a/src/include/SysYIROptPre.h b/src/include/SysYIROptPre.h
index db27b82..4f0bdca 100644
--- a/src/include/SysYIROptPre.h
+++ b/src/include/SysYIROptPre.h
@@ -19,7 +19,7 @@ class SysYOptPre {
   SysYOptPre(Module *pMoudle, IRBuilder *pBuilder) : pModule(pMoudle), pBuilder(pBuilder) {}
 
   void SysYOptimizateAfterIR(){
-    SysYDelAfterBr();
+    SysYDelInstAfterBr();
     SysYBlockMerge();
     SysYDelNoPreBLock();
     SysYDelEmptyBlock();
@@ -31,7 +31,7 @@ class SysYOptPre {
   void SysYBlockMerge();    // 合并基本块(主要针对嵌套if while的exit块，
                             // 也可以修改IR生成实现回填机制
   void SysYAddReturn();     // 添加return指令(主要针对Void函数)
-  void usedelete(); // use删除
+  void usedelete(Instruction *instr); // use删除
 };
 
 }  // namespace sysy
diff --git a/src/sysyc.cpp b/src/sysyc.cpp
index dc1015b..854ac53 100644
--- a/src/sysyc.cpp
+++ b/src/sysyc.cpp
@@ -9,6 +9,7 @@ using namespace antlr4;
 // #include "Backend.h"
 #include "SysYIRGenerator.h"
 #include "SysYIRPrinter.h"
+#include "SysYIROptPre.h"
 // #include "LLVMIRGenerator.h"
 using namespace sysy;
 
@@ -79,6 +80,10 @@ int main(int argc, char **argv) {
     auto moduleIR = generator.get(); 
     SysYPrinter printer(moduleIR);
     printer.printIR();
+    auto builder = generator.getBuilder();
+    SysYOptPre optPre(moduleIR, builder);
+    optPre.SysYOptimizateAfterIR();
+    printer.printIR();
     return EXIT_SUCCESS;
   }
   return EXIT_SUCCESS;