Abstract: Base on an observation systems and an artificial seismic source,Our research group conducted a 30-day field exploration experiment to measure accurately the seismic-wave velocity changes by the correlation test method.Experimental results show that the correlation test of the first arrivals made the measurement accuracy of seismic-wave velocity up to10-4 to 10-5.The seismic-wave velocity variation showed a synchronous relationship with the variation of groundwater level in a deep well near the test site.This means by the precise measurement of seismic wave travel time variety we can obtain the changes of the stress field and physical properties of the medium in the Earth's interior.