The invention provides an ion implantation phosphorus diffusion method matched with HF/HNO3 system selective etching, and the method can be used for preparing a high-quality phosphorus diffusion selective emitter so as to improve the conversion efficiency of a solar cell. The phosphorus diffusion selective emitter prepared by the ion implantation method is suitable for N-type high-efficiency battery production and phosphorus diffusion junctions serve as back junctions of an N-type cell, so the surface phosphorus concentration of a non-metal contact area of the N-type cell is reduced, auger recombination of the area is reduced, the open-circuit voltage of the cell is increased, meanwhile, it is guaranteed that the surface phosphorus concentration of a metal covering area is high, the ohimicresistance of the contact of a metal-silicon sheet is reduced, the fill factor of the battery is improved, and the conversion efficiency of the solar cell is finally improved.