This paper summarizes the reason why adjacent station have different wave velocity variation which measurement by air gun source in the same period. The results show that: ①The shape of the reservoir where the source located is irregular, and this lateral heterogeneity has little effect on wave velocity variation which measured by stations distributed around the reservoir; ②Fault zone has obvious influence on seismic wave propagation. Phase rays of adjacent stations have different paths when there exist fault zones. As the result, this will effect on the measurement results of wave velocity variation; ③Adjacent stations at different elevations may lead to seismic phase ray paths changed, but have little impact on the measurement results of wave velocity variation.