An engine valve movement switching mechanism comprises a cam shaft, an idler wheel, an idler wheel shaft and an idler wheel shaft box. Different cams are arranged on the cam shaft. The idler wheel shaft is arranged in an idler wheel groove of the idler wheel shaft box. The width of the idler wheel groove is larger than the axial length of the idler wheel. The idler wheel is rotationally arranged on the idler wheel shaft. The idler wheel can slide along the idler wheel shaft at different axial positions through an idler wheel axial drive mechanism, so that the idler wheel is switched to be connected with the different cams, and different engine valve movements are generated. The idler wheel axial drive mechanism comprises a piston drive mechanism integrated in the idler wheel shaft, and a drive piston in the idler wheel shaft is connected with the idler wheel on the idler wheel shaft through a drive pin. A reversing valve mechanism, an oil storage mechanism and a slow seat falling mechanism are adopted for shortening the valve movement switching time and reducing the valve movement switching impact. The engine valve movement switching mechanism can be used for engine braking including two-stroke braking, engine exhaust gas recirculation, engine cylinder closing, engine cold starting and different valve lifts and phases.