The utility model discloses an auxiliary air brake valve assembly of an automobile. The device comprises a mounting plate and a shaft pin, a valve body is fixedly mounted at the bottom of the mountingplate through a bolt; a tappet is embedded in the middle of the top surface of the valve body; the upper end of the tappet rod penetrates through the mounting plate and is connected with a brake pedal; a front half shaft pin is arranged at the front part of the shaft pin; a rear half shaft pin is arranged at the rear part of the shaft pin; an ejector rod is arranged in the middle of the bottom surface of the brake pedal; a front half ejector rod is arranged on the front portion of the ejector rod, a threaded rod is fixed to the middle of the surface of the rear end of the front half ejector rod in a welded mode, a rear half ejector rod is arranged on the rear portion of the ejector rod, a fixing head is welded to the middle of the surface of the front end of the rear half ejector rod, anda threaded hole is formed in the middle of the surface of the front end of the fixing head. The ejector rod and the shaft pin are fast and convenient to assemble, meanwhile, the damaged ejector rod and the damaged shaft pin are convenient to disassemble and replace, maintenance is easy, and the service life of the air brake valve can be prolonged.