The invention relates to the field of solar cell production. The invention provides a preparation method of a PERC solar cell. The method comprises the steps of texturing, diffusion, laser SE, back PSG removal, alkali etching and polishing, front PSG removal, annealing, aluminum oxide treatment, front antireflection film deposition, back laser grooving, screen printing, and sintering, wherein after laser SE, chain oxidation, ozone oxidation and back PSG removal and subsequent steps are sequentially carried out, in the chain oxidation step, a layer of oxidation film is plated on the surface subjected to phosphorus doping in laser SE, the thickness of the oxidation film is controlled to be 10-100 nm, the temperature is controlled to be 500-800 DEG C, and in the ozone oxidation step, ozone is introduced after the oxidation film is generated in the chain oxidation step to enhance the front protection effect, and the ozone concentration is controlled to be 10-100 ppm.