SiNx thin films were grown on quartz glass substrates and stainless steel by magnetron sputtering. Surface morphology of the films was investigated by scanning electron microscopy(SEM) and atomic force microscope(AFM), then the film surface dynamic evolution was analyzed by detecting size of roughness and grain. The results showed that SiNx thin films inquartz glass substrates were more uniformly and small particles than in the stainless steel substrates; Vacuum annealing helped the SiNx film particles refined, and reduced the surface roughness. During the range of sputtering power of 125W~175W, the average particle diameter of SiNx thin films up to 41.0 nm; Its rms and particle size impacted severely by Ar pressure when the sputtering power was 75W.