Ventilation system of engine

The utility model discloses a ventilation system of an engine, which is provided with an oil-gas separator, an oil return pipe, a ventilation pipe and an oil suction pump and comprises a crankcase, the oil suction pump, an oil pan oil collecting area, an integrated oil tank, a cylinder head cover and a first oil-gas channel. The oil suction pump is arranged in an oil pan of the engine and used forsucking engine oil from the oil pan. The oil pan oil collecting area is located on the lower portion of the crankcase. The integrated oil tanks are positioned on two sides of the crankcase; the cylinder head cover is arranged on the cylinder head; the first oil-gas channel is communicated between the cylinder head cover and the top of the integrated oil tank; when the oil suction pump sucks engine oil into the integrated oil tank from the oil sump oil collecting area, part of oil gas can be sucked into the integrated oil tank, so that the pressure of the oil gas on the upper portion of the integrated oil tank is incr