The invention provides a P diffusion method of a silicon wafer; a textured silicon wafer is subjected to P diffusion; in the P diffusion process, the steps of increasing the temperature for the first time, depositing for the first time, propelling for the first time, increasing the temperature for the second time, depositing for the second time, propelling for the second time, increasing the temperature for the third time, depositing for the third time, propelling for the third time, decreasing the temperature and absorbing impurities are carried out in sequence; by means of the depositing processes, the propelling processes and the impurity-absorbing processes step by step, the sheet resistance uniformity of the silicon wafer containing a PN junction is increased; the surface concentration and the junction depth are reduced; therefore, the conversion efficiency of the solar cell is effectively increased; furthermore, the method provided by the method is incapable of increasing existing production of production lines, and has better economic benefits.