Hydrocyclone is a liquid-liquid separation equipment commonly used in oil fields. It is mainly used to separate free oil particles suspended in liquid to meet the emission standards required by regulations. It uses the strong centrifugal force generated by the pressure drop to achieve high-speed swirling effect on the liquid in the cyclone tube, thereby centrifugally separating oil particles with lighter specific gravity to achieve the purpose of liquid-liquid separation. Hydrocyclones are widely used in petroleum, chemical industry, environmental protection and other fields. They can efficiently handle various liquids with different specific gravity, improve production efficiency and reduce pollutant emissions.