The invention discloses a biochemical sewage purification device which comprises a box body. An air bellow is fixedly installed at one end of the box body, an iron gauze is fixedly installed on the side, away from the box body, of the air bellow, a frame is fixedly installed on the periphery of the iron gauze, a control valve cabinet is fixedly installed on the upper end face of the air bellow, acabinet door is fixedly installed on one side of the control valve cabinet, a handle is arranged on the cabinet door, a fixing frame is fixedly installed on the bottom face in the box body and provided with a fixing hole, an installation base is fixedly installed at the bottom in the air bellow, an oxygen pump is fixedly installed on the installation base, an installation frame is fixedly installed on one side of the installation base in the air box, the output end of the oxygen pump is sleeved with a ventilation pipe, the ventilation pipe penetrates into the control valve cabinet, in the control valve cabinet, a first control valve sleeves the ventilation pipe, and an aeration pipe is fixedly arranged in the fixing frame. The biochemical sewage purification device is simple and reasonablein structure, novel in design, easy to operate, high in applicability, high in practicability and convenient to widely popularize and use.