Power loss is observed in photovoltaic modules resulting from the potential induced degradation (PID), which is mainly related with packaging glasses, glue film and surface treatment of solar cell. The coating process of solar cell to design the experiment is focused on. Thickness, refractive index, reflectance, minority carrier lifetime of the pre and post coating of silicon nitride (SiNx) anti- reflection coatings of machining standard process and preventing PID process and electrical characteristics of the solar cell are tested and analyzed. The results show that the PID process of mono-crystalline silicon solar cells have good passivation effect, but the anti-reflection effect of the poor is the main cause lead to the low conversion efficiency in the whole spectral range. Electro luminescence defect tests show that the preventing PID process does not bring additional defects to the mono-crystalline silicon solar cell, but solar cells are made by the preventing PID process when it is applied in modules have a resisting potential induced degradation phenomenon and preventing damage to solar cells from metal ion, compared with the standard process.