The utility model discloses a cyclone for oil field sewage treatment, set up the open -ended casing including the top, the casing is circular structure, equidistant welding has rectangular's fixed column on the lateral wall of casing, and the bottom inner wall of the bottom of fixed column and casing welds mutually, the both sides of fixed column have all been seted up the top and have been set up open -ended rectangular groove, and the welding has the slide rail on being located one side inner wall that two rectangular grooves on the same fixed column are close to each other, is equipped with the metal screen of camber between two adjacent fixed columns, and the bottom inner wall of the bottom of metal screen and casing contacts, and the both sides of every metal screen are fixed with the slide with slide rail sliding connection, and the top of slide extends to the top of metal screen, and four metal screens are the loop type distribution. The utility model discloses economical and practical, metal screen are convenient for dismantle from the inside of casing, and then are convenient for the staff and clear up the metal screen, have avoided the metal screen to take place to block up.