The invention discloses a combined three-phase separation device for an efficient anaerobic reactor. The combined three-phase separation device (1) is provided inside with several layers of three-phase separators (2) produced through one-time stamping; and each three-phase separator (2) passes through the three-phase separation device (1). A cross section of the three-phase separator (2) is preferably to be a triangle; and the combined three-phase separation device (1) can be a cuboid, a cube or a semi cylinder. According to the combined three-phase separation device, the three-phase separators are produced through one-time stamping, so as to reduce the workload of welding; the three-phase separators can be produced into finished products in advance and sent into a processing site for lifting, so as to avoid the situation of missed welding point; after lifting into the anaerobic reactor, the device is mainly fixed by screws for anchoring, so as to reduce damage on corrosion prevention of internal pieces; and the layers of the three-phase separators arranged inside can be adjusted according to the change of treated water quality, thereby realizing three-phase separation effect to the maximum degree.