diff --git a/src/mapleall/maple_be/src/cg/aarch64/aarch64_prop.cpp b/src/mapleall/maple_be/src/cg/aarch64/aarch64_prop.cpp
index 822dbb071c2b19f284f73aad3cb3f61175f024ef..b942b88a44f4f0741101c8df5a1159a917fcdbb0 100644
--- a/src/mapleall/maple_be/src/cg/aarch64/aarch64_prop.cpp
+++ b/src/mapleall/maple_be/src/cg/aarch64/aarch64_prop.cpp
@@ -1324,12 +1324,8 @@ bool CopyRegProp::CheckCondition(Insn &insn) {
           VaildateImplicitCvt(destReg, srcReg, insn);
           return false;
         }
-        if (destReg.GetValidBitsNum() >= srcReg.GetValidBitsNum()) {
-          destReg.SetValidBitsNum(srcReg.GetValidBitsNum());
-        } else {
-          CHECK_FATAL(false, "do not support explicit extract bit in mov");
-          return false;
-        }
+        destReg.SetValidBitsNum(srcReg.GetValidBitsNum());
+
         destVersion = optSsaInfo->FindSSAVersion(destReg.GetRegisterNumber());
         ASSERT(destVersion != nullptr, "find Version failed");
         srcVersion = optSsaInfo->FindSSAVersion(srcReg.GetRegisterNumber());