Abstract: Abstract: In the current, due to the shortage of energy, greenhouse effect and serious pollution of ecological environment, the development and utilization of biomass energy can meet the objective law of sustainable development, promote the adjustment of energy structure in China, reduce dependence on fossil energy, and increase the renewable energy utilization ratio. It can help to alleviate various ecological environmental pollution and damage caused by the current fossil energy use, and establish the clean renewable energy system. And it can be conducive to broaden the human energy utilization scope, alleviate the pressure of energy shortage and improve life quality of the people. Compared with biomass gasification and oil production, biomass carbonization has the advantages of low cost, low equipment requirement and is used widely. Except for being used as fuel, it can also be used to improve the soil adsorption of heavy metal, pesticides, pollutants, and so on, reduce greenhouse gas emissions and improve the water quality. Biomass pyrolysis technology has made some progress, but it still remains in the technology level of charcoal preparation in traditional kiln, and it has disadvantages of low carbon rate, poor quality, high labor intensity, poor working environment, serious environmental pollution, low efficiency and long period, so biomass carbonization is not applied in large area. In order to effectively solve the problems of the present biomass carbonization equipment of carbon preparation, such as low carbon yield, poor quality of the carbon, the surplus gas to pollute the environment, the by-products being not effectively separated, a set of biomass carbonization equipment with exhaust gas self-circulation is designed and manufactured. Carbonization furnace body, heating system, tar recovery device, gas circulation device, and temperature and pressure monitoring system are designed in detail and the parameters are set. The finite element method is used to study the heat transfer performance of the carbonization furnace body and tar recovery device. In the end, the carbonization test is carried out. The results show that the biomass carbonization equipment can meet the demand of carbon preparation, by-product recovery, waste recycling, precise control of process parameters for the furnace door frame. The upper temperature distribution is uneven, the internal temperature distribution of the furnace body is uniform and the temperature gradient of biomass can be smooth. The flow rates at the 3 cooling water inlets of the tar recovery device are 0.045, 0.03 and 0.015 m/s, respectively, and the temperature decline during the cooling is 271, 111 and 61 ℃, respectively. The temperature of flue gas cools from 500 to 50 ℃. The cooling effect is obvious, and volatile of tar can be separated from wood vinegar liquid. The influence order of the factors of carbon yield, calorific value and energy yield is as follows: Carbonization temperature > holding time > heating rate. The carbon yield has positive correlation with the energy yield, and both have negative correlation with the heat value. Considering comprehensively, the best carbonization conditions are the heating rate of 3 ℃/min, the carbonization temperature of 450 ℃ and the holding time of 3 h.