In the manufacture of crystalline silicon solar cells, it is important to control the diffusion quality for improving the cell quality and efficiency. On the basis of analyzing the effect of the diffusion uniformity on the equipment and the craftwork, the experimental methods for the optimizing diffusion uniformity are presented, including P diffusion is slowed down using SiO2 sheet, the flux of N2 and O2 is controlled in the diffusion, the effect of the temperature fluctuation on the diffusion result is reduced, the temperature is compensated by setting the high temperature in the throat opening, the pressure is adjusted for achieving the dynamic balance. The experiment shows that these methods are helpful for improving the performance of solar cells and guiding the production of industrialization.