A detailed study of ray tracing, tomographic inversion method and numerical tomographic inversion algorithm were performed and, on such a basis, the method of using first arrival of shot to directly establish the initial seismic model was put forward. In addition, the tomographic inversion of near-surface velocity model process flow with reference to the refraction and logging and the high-precision rapid ray tracing method by multi-retracing and SIRT tomographic inversion were also suggested. The double grid technology was employed to improve modeling simulation accuracy and tomographic inversion imaging quality and, what is more, the multiple quality control plans were fully considered to ensure the precision of the final inversion velocity model. The ray tracing, tomographic inversion, graphics display and some other programs were developed, 10 different theoretical surface geological conditions were designed, the theoretical model was tested, and seismic data from Shengli, Sichuan and some other areas were studied. The results of tomographic inversion calculation and actual data inversion prove the correctness of the theoretical research.