The invention discloses an aluminum-induced low temperature preparation method of large grain size polysilicon film; the grain size of the prepared polysilicon film reaches above 100 microns and the polysilicon film has smooth surface. The method comprises the following steps: (1) depositing amorphous silicon film on a substrate 2; (2) continuously generating silicon dioxide film; (3) continuously depositing aluminum film to obtain substrate/a-Si/SiO2/Al lamination; (4) placing the substrate/a-Si/SiO2/Al lamination in a vacuum annealing furnace to perform three-step annealing under the protection of inert atmosphere; (5) using aluminum corrosive liquid to corrode and remove the residual aluminum on the surface. The method of the invention can prepare polysilicon film with large grain sizeon the cheap substrate at low temperature and the crystallization orientation and surface roughness are controllable, thus the method has broad application prospect in fields such as film solar cellsand the like.