J-integral is the parameters of stress and strain fields near the crack tip. The smaller the J-integral, the less chance to extend the crack is. In this paper, the treatment is taken on the thin plate with crack by the surface self-nanocrystallization, which can improve mechanical property of the material. 316L stainless steel is being used as the basic material. And the simulation software of ABAQUS is being used to make a simulated calculation to get the results of J-integral near the crack tip. The results show that the J-integral near the crack tip of the thin plate with crack is obviously reduced after part of surface being disposed by nanocrystallization. Then, comparing different methods being taken on the structure, the best way is that the ellipse area near the crack tip being disposed by nanocrystallization, the others keep raw material. And the long axis of the ellipse is perpendicular to the crack.