Abstract: With the increasingly strict requirements of environmental protection,the environmental problems caused by the fixed bed gasification tar have become a bottleneck for restricting the development of fixed bed gasification technology,and low tar gasification should be paid more attention to. This paper introduces the approach and influencing factors of low tar gasification in fixed bed gasification,analyzes the influence of various technological conditions on tar yield,and expounds the principle of reducing tar in two-stage gasifier,downdraft gasifier and two-stage air supply gasifier. It is more common to combine downdraft gasifier with two-stage gasifier to produce low tar content,high gas heat,low heat loss rate in the furnace,which is mostly used for biomass gasification technology development. The throat structure can not only increase the gas velocity,but also increase the temperature in the blast furnace and promote tar cracking in the furnace. Gasification raw materials,particle size,gasification process( gasification final temperature,pressure,gasification agent,catalyst,etc.) are important factors of affecting the yield of tar. The high volatile gasification raw materials( low rank coal,biomass,etc.) produce more tar,and the content of low volatile high rank coal tar is very little. The particle size affects volatile analysis precipitation and heat transfer,which affects tar yield. The influence of temperature mainly lies in tar cracking. When the tar cracking occupies the main reaction position of cracking reaction,the yield of tar gradually decreases with the rise of temperature. Therefore,some catalysts and subsequent de-tar technology need to reduce the tar content according to the thermal cracking effect of temperature on tar. Increasing pressure will inhibit volatile analysis,which is conducive to reducing tar. The suitable amount of water vapor can reduce tar content,and increase the hydrogen content,but will reduce the gasification temperature,and the quantitative parameters need to be adjusted. Various catalysts can effectively reduce the tar content and change the heat value of gas,but the strict catalyst reaction conditions will increase the cost of gasification. The realization of low tar gasification is an important breakthrough in fixed-bed gasification technology,which can not only improve the utilization rate of low-rank coal,but also solve the problem of high volatile biomass and urban waste gasification,and generate clean new energy. The content of tar in gas is reduced,the effective gas composition is increased,which can alleviate the problem of low heat value of gasification raw material.