The invention discloses an oil-gas separator of a supercharged engine, and the oil-gas separator comprises a cavity, a gas inlet, a gas outlet and an oil return port, wherein inside of the cavity is provided with an oil-gas separation mechanism, the gas inlet is arranged on the cavity and used for allowing oil gas inside a crankshaft box to enter the cavity, the gas outlet is arranged on the cavity and used for allowing the separated gas to flow out of the cavity, the oil return port is arranged on the cavity and used for returning the separated engine oil to an oil bottom shell, and the oil-gas separation mechanism comprises at least one arc baffle plate which is arranged along the height direction of the cavity. The oil-gas separator can effectively improve the oil-gas separation efficiency and guarantee the returning smoothness of the separated oil. The oil-gas separator is applicable to ventilation systems of different supercharged engine crankshaft boxes.