A method for preparing a nanometal-polymer composite conductive film includes the steps of (1) mixing a metal oxide with a polymer solution; (2) coating a substrate with a solution resulting from step (1), followed by drying the resultant solution to form a film; (3) performing thermal treatment on the film formed in step (2); and (4) sintering the film thermally treated in step (3). The method dispenses with any reducing agent or dispersing agent but allows nanometallic particles to be formed in situ and thereby reduces surface resistance of the polymer film efficiently.