Using laser repair technology to repair cracks can effectively improve the fracture performance of parts.This paper takes 304 stainless steel compact tensile specimens as the research object, and establishes thermal analysis and mechanical analysis finite element models respectively. First, the temperature field distribution of the repair area around crack tipunder different laser process parameters was simulated, and the relationship between the dilution rate and the laser parameters was analyzed. Furthermore, the material composition of the repair zone was obtained from the relationship between the matrix material composition, the repair powder material composition and the dilution rate. Finally, the J-integral of the crack tip of the repaired 304 stainless steel specimen was simulated, and the influence of laser parameters on the J-integral of the crack tip was analyzed. The results show that when the laser spot diameter and heating time are constant, as the laser power increases, the J-integral at the crack tip decreases first and then increases, and the repair specimen has better fracture performance when the laser power is 1 800 W; When the power and heating time are constant, as the spot diameter increases, the J-integral at the crack tip decreases first and then increases. When the spot diameter is 3 mm, the repaired specimen has better fracture performance.