Abstract: The embedded systems design pay less attention to safety out of consideration for cost and power consumption, and the software defense mechanism unable to achieve the requirement of the embedded systems in real-time and reliability, as the most common software vulnerabilities, buffer overflow poses a serious threat to embedded systems in safety.So we build a hardware defense mechanism based on fine granularity instruction flow monitor to against buffer overflow attacks, through virtual implement the procedures by ours virtual execution units, we can detect attacks before it come comply.The result shows that the hardware defense mechanism can defense these attacks completely, and neither change the source code or destroy the pipeline integrity, nor affects performance, our protection mechanism could be used to prevent run-time buffer overflow attacks in other embedded systems.