The invention relates to sewage treatment facilities, and aims to provide a plastic oil separation system which is specialized in treatment of wastewater with high oil content, including restaurant wastewater and the like. The oil separation system comprises a rough filtration tank and an oil-water separation tank, wherein a filtering frame is arranged in the rough filtration tank, and a water outlet of the filtering frame is communicated with a water inlet of the oil-water separation tank; a first oil slick bin, a second oil slick bin and a third oil slick bin are sequentially arranged between the water inlet and the water outlet of the oil-water separation tank, and a cleaning opening is formed above each oil slick bin; and a water passing hole of each of the first and second oil slick bins is positioned at the middle-lower part in each bin, and the water outlet of the oil-water separation tank is formed in the upper part of the third oil slick bin. Repeated three times of oil-water separation ensures the separation effect. The wastewater without oil can be directly discharged generally; and other wastewater with more organic substances or harmful substances is subjected to further harmless treatment, and because the oil and organic substances are separated, the wastewater treatment difficulty can be significantly reduced.