Plasma enhanced chemical vapor deposition (PECVD) silicon nitride (SiNx) and SiO2 have been widely used in microelectronic and photovoltaic silicon solar cells as dielectric, because of low deposited temperature and compatibility with other possess, SiNX gradually becomes the first choice in industry silicon solar cells production. Nowadays, in photovoltaic silicon solar cells, the excellent antireflection and passivation quality of PECVD SiNx have obvious effect on efficiency of solar cells. In this paper, we analysis several critical parameters for PECVD SiNx deposition, such as temperature of substrate, plasma RF power, ratio of NH3/ SiH4 and annealing temperature, and to investigate the optical and passivation property of SiNX, through MW-PCD for minority lifetime and ellipsometry measurement for SiNX thin film refractive indices, thickness and extinctive coefficient; we theoretically investigate the correlation between the deposition temperature, ratio of NH3/SiH4, annealing temperature with effective lifetime, refractive indices and use several model to explain them. At last, we propose a set of optimized parameters for PECVD-SiNX deposition in silicon solar cells.