The utility model discloses an efficient coal gasification black water precipitation separation device which comprises a shell, an inclined plate combination device, a flocculating agent mixing and stirring tank, a flocculation reaction stirring tank, a discharge aiding stirring device and a discharge aiding stirring rake frame, the flocculating agent mixing and stirring tank and the flocculationreaction stirring tank are respectively provided with a speed-adjustable stirrer, are communicated with each other and are communicated with the interior of the shell; the material and a flocculatingagent are mixed in the mixing and stirring tank and then flow into the inclined plate combination device in the shell through the flocculation reaction stirring tank for shallow sedimentation; a concentrate collecting area is arranged at the lower part of the shell, the discharge-assisting stirring rake frame is arranged in the concentrate collecting area, and the discharge-assisting stirring device is in transmission connection with the discharge-assisting stirring rake frame; a clarified water overflow groove is formed in the upper part of the inclined plate combination device and is communicated with the outer part of the shell. When materials with low concentration, low specific gravity, fine particles and micro-fine particles are flocculated, the concentration ratio of the materials can be greatly improved, and the purification and clarification efficiency of the materials is improved.