20mg/m3以下。A novel and efficient low-tar gasification technology was put forward based on the mechanics of tar generation and pyrolysis. This technology contains such two separate sub-process as pyrolysis occurring between 350℃ and 500℃, and gasification reacting in the high temperature condition about 1000℃. The high-temperature gasification ensures the tar pyrolyze into small molecule non-condensable gases with the equivalence ratio of gasification agent about 0.3. As a result, the quality of biogas is highly improved and the mass concentration of original tar in the biogas is significantly reduced below 20 mg/m3.