A rocker arm mechanism includes a rocker arm shaft, a rocker arm, a valve clearance adjuster, a valve train, and a control valve. The rocker arm is rotatably disposed on the rocker arm shaft. The valve train includes a valve bridge. The rocker arm is provided with a plunger chamber. The valve clearance adjuster includes a hydraulic tappet slidably disposed in the plunger chamber. The plunger chamber is supplied with oil through an oil supply passage. The control valve is configured to open or close the oil supply passage. When the control valve opens the oil supply passage, the hydraulic tappet can abut against the valve bridge and eliminate the clearance between the valve bridge and the hydraulic tappet.