Drain plug assembly

The invention discloses a drain plug assembly, and relates to a drain plug installed on an engine sump. The drain plug assembly comprises a plug and a gasket, the gasket is a flat gasket or a rubber product, ring grooves are manufactured on the two lateral faces of the gasket, a cavity for containing the gasket is arranged on a flange face of the plug, and the distance between the two lateral faces of the gasket is larger than or equal to two times of the depth of the cavity; a bulge loop is arranged on the inner lateral face of the gasket, the distance between the two lateral faces of the bulge loop is equal to 0.45 time to 0.55 time of the distance between the two lateral faces of the gasket, and the diameter of the inner lateral face of the bulge loop is equal to the diameter of the plug. The drain plug assembly has the beneficial effect that the torque needed when the plug is screwed up is smaller; and after the plug is screwed up, the drain plug assembly has the beneficial effects that the sealing effect is good, oil seepage and leakage is not prone to occurrence, and the cost for machining, manufacturing, using and maintaining is low.