Surface defects generated by grinding deteriorate the flexural strength of the silicon nitride ceramic. In this paper, laser surface processing was applied to eliminate the grinding-induced defects. SEM micrograph showed that the surface integrity of samples was improved after laser processing. Four-point bending tests and fractographic analysis indicated that the flexural strength and fracture origins were affected by the change of surface integrity in laser-treated samples. The effect of grinding-induced residual stress on flexural strength of laser-treated samples was discussed. It was concluded that laser surface processing had significant effects on fracture behavior of flexure samples.