The invention discloses a preparation method of an antibacterial NCC (Nanocellulose) film. The method comprises the following steps: (1), dispersing NCC of which a surface is negatively charged into deionized water, and carrying out ultrasonic treatment and standing to obtain NCC dispersion liquid; (2), producing an NCC film by using the NCC dispersion liquid in the step (1) through a filtration method, so as to obtain the NCC film of which the surface is negatively charged; (3), carrying out spraying treatment on the NCC film of which the surface is negatively charged and which is prepared in the step (2) by using a silver nitrate aqueous solution for 1 to 10 times according to the specification of 50 to 200mL/m<2>, and drying after the spraying treatment every time, so as to obtain the NCC film with Ag<+> deposited on the surface. The invention provides a new preparation method of the antibacterial NCC film with Ag<+> deposited on the surface, and the method is simple and feasible, and is low-cost; moreover, the size and the antibacterial performance of the NCC film can be regulated and controlled, the NCC is wide in source, and therefore, the NCC has good practicability.