A preparation method for a multilayer graphene quantum carbon-based two-dimensional semiconductor material comprises: S1. taking a PI film as a raw material, and performing polymer sintering at a first temperature, to remove H, O and N atoms to form a carbon precursor; and S2. adjusting the temperature to a second temperature, and graphitizing the carbon precursor to form a multilayer graphene quantum carbon-based two-dimensional semiconductor material, wherein in at least the step S2, a nano metal material is doped to form quantum dots in the multilayer graphene. The multilayer graphene quantum carbon-based two-dimensional semiconductor material prepared by the method adopts a hexagonal planar net molecular structure, is orderly arranged, and has flexibility, high tortuosity, and quite low in-plane dispersity and degree of deviation. Band gaps are formed through doping of a nano metal, and the band gaps are controllable.