A method of fabricating MOSFET device with polycide gate, which includes a polysilicon layer and a refractory metal silicide layer, is described. After a thin oxide layer is formed by a thermal process, the refractory metal silicide layer is transformed from an amorphous form to a crystalline form that leads to peeling and surface roughness problems in the prior art. This method utilizes an additional ion implantation step to transform the refractory metal silicide layer from the crystalline form back into the amorphous form. Hence, the problems of peeling and surface roughness of the polycide gate can be overcome.