The invention discloses a preparation method of polyvinylidene fluoride resin, comprising: polymerizing, washing and drying of polyvinylidene fluoride monomer; the polymerizing step uses a dispersant system with a combination of organic and inorganic dispersants according to a molar ratio of 1:(1-5), adding according to parts by weight: 100 parts of deionized water, 0.003-0.09 part of the dispersant system, 0.01-0.1 part of an initiator, 0.001-0.1 part of a chain transfer agent and 20-38 parts of VDF monomer into a polyermizer, and polymerizing at 40-80 DEG C for 5-18h and then ending the reaction. The polyvinylidene fluoride resin prepared by means of suspension polymerization has excellent heat resistance.