Abstract: Based on the thermo-mechanical coupling characteristics of rocks, the temperature field and stress field in 1 000 years after excavation and backfill were calculated by using finite element program ABAQUS, and the evolution laws of temperature field of the nuclear waste repository and stress field of surrounding rocks and buffer material were obtained. The results show that the maximum temperature at the center of nuclear waste reaches 116℃ in 6.3 years after dispose, then decreases gradually and finally goes into the slow decreasing period. The conductivity of buffer material has great influence on temperature field of surrounding rocks, the higher the conductivity is, the lower the maximum temperature at the center of nuclear waste is. After backfill of the disposal tunnel and pit, the tensile stress of surrounding rocks is very large which is very close to the tensile strength and there are risks of tensile fracture failure. The tensile and compressive stresses are both very high in buffer material, tensile fracture failure could occur at the intersection of the disposal tunnel and pit, and compressive fracture failure could occur at the floor of the disposal tunnel.