In the process of 3D seismic exploration of coal field, the overburden thickness was obtained by small refraction, micrologging and borehole data, but because the points were scattered, only the overburden thickness value of that point was obtained, and even the overburden thickness map obtained by refraction static correction software cannot meet the accuracy requirement because of the limited velocity point map pulled. To address this problem, the large amount of first arrivals information in the seismic record was made, and the pick-up first arrivals were adopted to calculate the direct and refracted wave velocities to find the thickness of the overburden in the whole area, and this thickness with reference to the borehole data and small refraction data were corrected to make the overburden thickness measurement more accurate.