A valve bridge has a valve bridge body being provided with a main piston chamber, an actuating pin mounting chamber, a main piston, and an actuating pin; an elastic member is arranged between the actuating pin and the actuating pin mounting chamber, and a lower end of the actuating pin extends out of the actuating pin mounting chamber under an elastic force of the elastic member; the valve bridge body is provided with a first oil drainage passage in communication with the main piston chamber, and an interior of the actuating pin is provided with a second oil drainage passage having one end in communication with a return oil chamber of an engine.