Abstract: Using earthquake catalog and travel time difference data obtained from seismic dataset in Sichuan-Yunan region by APP++ and cross-correlation, we refine the earthquake locations and inverse the three-dimensional P-wave and S-wave velocity structure of the crust in the region through double-difference tomography. The earthquake distribution after relocation well describes the related fault geometry; the velocity structure in shallow depth can well match the distribution of the faults in the region, and the velocity structure in deep roughly reflects the crustal flow feature in Sichuan-Yunnan rhombic block.