The present invention relates to a polyvinylidene fluoride preparation method, which comprises: introducing an acyl halide solution dispersed in a fluorine-containing organic solvent into a reaction kettle, adding a mixed solution comprising an inorganic alkali solution and hydrogen peroxide, carrying out a stirring reaction for 30-120 min at a temperature of -10-10 DEG C, carrying out in situ synthesis to obtain an initiator, introducing an aqueous solution of a dispersing agent, a vinylidene fluoride monomer and a chain transfer agent, carrying out a stirring reaction for 4-12 h at a temperature of 10-30 DEG C to prepare polyvinylidene fluoride, and carrying out filtering, washing, drying and crushing after completing the reaction to obtain the powdery product which is polyvinylidene fluoride resin powder. The powdery polyvinylidene fluoride resin has characteristics of good thermal stability, good physical property, good mechanical property, simple reaction process and easy control, and is suitable for industrial production.