The utility model provides a crankcase ventilation system for supercharged engine, relates to a crankcase ventilation system. The utility model discloses a solve present crankcase ventilation system oil -gas separation inefficiency, crankcase pressure is unstable, the problem of extreme environments galloping. The utility model discloses a side maze structure and the exhaust side maze structure of admitting air is all integrated on valve mechanism cover, the structural PCV of the installing valve in side maze that admits air, and the PCV valve is through breathing hose connection air intake manifold, and the structural pipe connector of installing in exhaust side maze is chewed, and the pipe connector is chewed through air hose and intake -tube connection, constitute the maze between the return flange of exhaust side maze structure and the valve mechanism cover bounding wall, two mazes about the orifice plate divide into the maze, the upper end of orifice plate be the suspension state, and the lower extreme of orifice plate passes through the bridging roof beam to be installed on the return flange, and the guide plate is installed in the left part maze, has seted up the gas blowby on the return flange and has entered the mouth. The utility model discloses oil -gas separation is efficient, crankcase pressure stability, extreme environments smooth operation.