The glass fiber reinforced plastic grease trap is an efficient and unpowered oil-water separation device newly developed on the basis of the traditional oil-water separation tank, which can recycle more than 91% of waste oil, effectively protect the environment and save a lot of operating costs. It is widely used for oil-water separation of oily water containing all kinds of mineral oil (except crude oil), vegetable oil, animal oil or their mixture, such as the treatment of oily sewage produced in restaurants, restaurants, factories, hospitals, schools, institutions, auto repair shops, oil stations, industrial and mining enterprises and other places, which can completely solve the problems of environmental pollution and sewage blockage and overflow caused by oil solidification in cold seasons.