The utility model provides a three -phase separator, four reflection collecting boaries all are located the UASB pond to the collecting board is respectively reflected to the messenger has contained angle alpha with UASB pond inner wall surface. Superficial residue separator installs the top of four reflection collecting boaries after the combination. Three heterotypic separator is installed respectively to lower surface at each reflection collecting board. The utility model discloses what prolonged come -up mud hits the plate circuit directly for the gas that mud was swept along can effectually release, improves gas release efficiency. Through special -shaped separator realized rivers through the time sweep along gaseous and mud effectively separate, has improved return sludge and has rateed, the separation of dross and the collection of gas have been realized through floating residue separator. The utility model provides a low, the air duct of general separator separation efficiency easily block up to and the difficult problem of dross separation, and simple structure, easy manufacturing have, and the low characteristics of the through engineering approaches degree of difficulty.