A film winding machine includes a main body and an automatic cutting-off roll-replacing mechanism. The main body has a winding reel, a standby reel, and an intermediate redirecting reel. The automatic cutting-off roll-replacing mechanism has a supporting frame which is fixed to the main body. The first swing unit is rotatably connected to the supporting frame along a forward direction. The first pressing roll abuts against one side of the standby reel. The second swing unit is rotatably connected to the first swing unit. The second pressing roll contacts the other side of the standby reel. The slicing unit is used to cut the film. The film is wound on a new standby reel, so as to complete tasks of automatically cutting-off and roll-replacing.