Chemical bond in single-layer and double-layer SiNx film, N/Si ratio and atomic percentage of Si、N、C、O are analyzed by X-ray photoelectron spectroscopy (XPS) in this paper. The impact of single-layer and double-layer SiNx film deposited by plasma enhanced chemical vapor deposition (PECVD) on mono-crystalline silicon solar cells electrical characteristic is verified. Analyses of XPS、reflectivity and minority carrier lifetime show that the film of SiNx with H atoms is generated on the mono-crystalline surface through NH3 and SiH4. The N/Si ratio of outer film of double-layer SiNx is slightly higher than that of single-layer SiNx, which play the better effect on anti-reflection. And the internal film had a better passivition effect than single-layer film because of richer Si. The electrical characteristic test shows that, comparing with single-layer SiNx film solar cell, open circuit voltage, short circuit current and photoelectric conversion efficiency of double-layer SiNx film solar cell improve by 2 mV, 47 mA and 0.17% respectively.