The invention discloses a preparation method of a high-flux PVDF porous membrane. The method comprises the following steps: mixing PVDF, a highly hydrophilic polymer, a pore-forming additive, deionized water, a solvent and graphene powder, curing, stirring, standing, defoaming so as to obtain membrane casting liquid, and forming a wet membrane from the membrane casting liquid in a scraping manner; pre-evaporating the wet membrane in air, putting the pre-evaporated membrane in a solidification bath, and soaking to obtain a primary membrane in the deionized water; putting the primary membrane in the deionized water, performing heating activation, soaking in absolute ethyl alcohol and n-butyl alcohol, and airing in the air. According to the method, graphene nano-particles with two-dimensional structures are used as additives, the pure water flux can be up to 800L*m<-2>*h<-1> or more, and the rejection rate on bovine serum albumin is 98% or more; the hydrophilic polymer is added for performing the activation on the primary membrane, so that the hydrophilia of the PVDF membrane is greatly improved, and the membrane surface contact angle is up to 59.8 degrees; a porous membrane material is adopted, so that the structure is controllable, and the pore diameter range is controlled to be within 0.1-5 microns.