Automobile speed reducer capable of achieving efficient lubrication and work method of automobile speed reducer

The invention belongs to the technical field of automobile speed reducers, and particularly relates to an automobile speed reducer capable of achieving efficient lubrication. The automobile speed reducer comprises a motor, a second installing plate arranged at the transmission end of the motor, and a gear case located on one side of the second installing plate and welded and fixed to the second installing plate. A first installing plate is welded and fixed to the face, away from the second installing plate, of the gear case. A transmission shaft of the gear case penetrates through the first installing plate. A transmission shaft is fixedly arranged on the transmission shaft of the gear case. A ball bearing is clamped to the transmission shaft, a power source is conducted for the motor, a transmission shaft of the motor drives the gear case to rotate, the transmission shaft of the gear case is used for driving the transmission shaft to rotate, and when the motor rotates, vibration is generated, lubricating oil