Biomass tar is produced as a by-product in the pyrolysis process of biomass, which is difficult to remove and harm to human health. The physical and chemical properties of pyrolysis tar were analyzed and it was fond that it had a high calorific value. After combustion, it can provide heat source for pyrolysis equipment and realize energy recycling. Aiming at the problems of poor atomization effect and unstable direct combustion of pyrolysis oil, a secondary atomizing nozzle was designed. And a mixed combustion process of biomass pyrolysis tar and pyrolysis gas was proposed. And a certain amount of pyrolysis gas was used as a combustion supporting agent to provide a stable flame for the combustion of the pyrolysis tar. And a test system for pyrolysis oil combustion was developed. The burning test of tar showed that the burning quantity of tar in the burner was 20~55kg/h, which met the design requirement. And when the atomizing air pressure was 0.6MPa, the pyrolysis oil pressure was 0.2~0.4MPa, the gas pressure was 0.3~0.5kPa, the burner was burned stably and the flame was bright. Through the analysis and test of the flue gas analyzer, it was fond that the content of CO and NOx in the combustion flue gas was high, which showed that the primary combustion in the combustor did not achieve the ideal combustion effect. Therefore, it was suggested that the next step was to improve the combustion chamber and reduce CO and NOx emissions by secondary air distribution combustion of the burned flue gas.