Silicon nitride ceramics were prepared by pyrolyzing the thiol-vinyl silizane polymer derived precurosors cured by UV.The pyrolysis behaviors of precurosors with different weight ratio of thiol to vinyl silizane were studied by TGA,and the ceramic phase compositions and the microscopic structures of samples were characterized by XRD and SEM,respectively.The results showed that there were two peaks of rate of mass loss at 325~350℃ and 475~505℃ in DTA pattern,and the value of the peaks enhanced with increasing the amount of thiol compound.Moreover,the crystallinity,the size of grain increased and the relative density,the yield rate of the ceramic decreased with incorporating more thiol compound.α-Si3N4 crystals were formed after pyrolysis under 1400℃ for 15h.α-Si3N4 could partially be converted into β-Si3N4 by prolonging pyrolysis time.The fiber-like and sheet crystals of nitrogen-rich SiNx were found in the holes of the microstructure.