Abstract: According to the material properties of Cr18Mn18N austenitic stainless steel and the grinding characteristics of difficult-to-machine material, a 3-D FEM simulation for the surface grinding process was carried out using rectangular and trianglar heat source models to obtain the temperature distribution and thermal stress distribution of a workpiece. The effects of heat source model, grinding depth on grinding temperature field and thermal stress field were analyzed. Contrast analysis with 45 steel has been done to verify the validity of the model of grinding process. The maximal grinding temperature of Cr18Mn18N austenitic stainless steel reached 651 ℃, and maximal grinding thermal stress reached 285 MPa. The simulated result coincided with experimental result of 45 steel, which proved the grinding model for Cr18Mn18N steel was reliable.