Abstract: MILD combustion of pyrolysis gas is one of the key technologies for efficient conversion and utilization of organic solid waste．Compared with traditional single-component gas，solid waste pyrolysis gas has the characteris-tics of complex components，low heat value and poor combustion stability． In order to improve the efficient and clean utilization of solid waste pyrolysis gas，the effects of different fuels，air excess coefficients and air inlet cross-sectional areas on the combustion characteristics of solid waste pyrolysis gas and its MILD combustion formation conditions were studied with numerical simulation methods． The research results show that，compared with the sin-gle components of methane，the combustion process of the solid waste pyrolysis gas is sped up because of its high hydrogen content． In addition，its peak temperature is high，and its temperature field is unevenly distributed．Changing the air distribution conditions at the inlet of the combustion chamber has a significant impact on the com-
bustion process． With the reduction of excess air coefficient，the peak temperature in the combustion chamber de-creases，the overall temperature level rises，and the temperature distribution becomes more uniform，but at the same time the range of the high temperature region also increases significantly，resulting in an increase in NO con-tent at the outlet． Under the condition of low excess air coefficient，the reduction of the air inlet cross-sectional ar-ea can reduce the peak temperature in the combustion chamber，and the uniformity of temperature distribution can be effectively improved． In order to achieve MILD combustion of solid waste pyrolysis，the content of NO at the outlet should be reduced to no more than 0. 003%．

Key words: organic solid waste, solid waste pyrolysis gas, air excess coefficient, air inlet cross-sectional area, MILD combustion, temperature distribution, NO content at the outlet