Abstract: The principle of the elastic wave method detecting the barrier post embedded length in soil was described.The involved factors,which impacted the test results were analyzed by experiments,such as the sensor type and its installation location,vibration hammer and the ways for exciting vibration,whether or not to be connectted to the quardrail,the relative position between the guardrail plate and the post etc.It provids the theoretical and experimental proofs for engineering test and developing portable inspection equipment.