The invention discloses a back door opening and closing track rectifying device and method. The back door opening and closing track rectifying device comprises a rack. A back door mounting base is slidably connected to the rack in a matched mode. The rack is fixedly connected with a length position adjusting mechanism used for driving the back door mounting base to move horizontally. A back door mounting bracket is slidably connected to the back door mounting base in a matched mode. The back door mounting base is fixedly connected with a height position adjusting mechanism used for driving theback door mounting bracket to move vertically. The back door mounting base is connected with a back door fixed plate which can be opened and closed. A telescopic supporting rod is connected between the back door fixed plate and the back door mounting base. The end of the back door fixed plate is connected with a telescopic back door moving plate. The structure is simple and application is convenient. The device and method ensure operation comfort of the back door with respect to a vehicle rear protection in different positions, heights and radii.