In the cold state, the engine cylinder liner, piston, connecting rod and other engine parts are bonded together, resulting in the reaction force of engine rotation. However, the diesel engine is compression-started, and it must have a certain speed to ensure sufficient compression ratio, so as to ensure the engine start. At the same time, the air circulation system of the intake and exhaust system in the cold state has not been started, which is especially unfavorable for supercharged engines.