Gasification fine slag is mainly stacked and landfilled at present,and the pressure of environmental protection is high. How to efficiently utilize gasification fine slag with low calorific value is a hotspot at present. The total amount of the two kinds of gasification fine slag discharged from the gasification process of methanol synthesis and kerosene is large, which is difficult to dispose. Through particle size analysis and SEM observation of two kinds of gasification fine slag, it is found that the particle size of gasification fine slag is small, most of which is less than 100 μm. The structure of gasification fine slag is broken, consisting of many spherical particles formed by melt polymerization and irregular pores. Co-firing is an effective method to use low calorific value fuels. The gasification slag was mixed with coal and biomass in different proportions to analyze the combustion characteristics, and the Coats-Refern method was used to analyze the kinetic characteristics. It is found that cofiring of gasification fine slag with coal and biomass can greatly improve the combustibility of gasification fine slag and reduce the activation energy for combustion. The activation energy of methanol slag and kerosene slag is 105.10 kJ/mol and 100.80 kJ/mol respectively. When the proportion of gasification fine slag is 30% after mixed combustion of methanol residue, kerosene residue and coal, the comprehensive combustion characteristic index is the highest, which is 23.64×108 and 25.96×108 respectively. Meanwhile, the activation energy is the lowest, which is 89.46 and 83.76 kJ/mol respectively. The gasification fine slag con tains abundant pore structure. A certain proportion of gasification fine slag mixed with coal can increase the contact area between combustible materials and air, facilitate gas adsorption and diffusion, shorten the time to reach the maximum combustion rate, and advance the maximum combustion intensity. The activation energy of methanol slag and kerosene slag cofiring with biomass is the lowest when the proportion of gasification fine slag is 30%, which is 72.14 and 69.59 kJ/mol respectively. The combustion temperature of biomass is lower than that of gasification fine slag, which can preheat the combustion process of gasification fine slag and significantly reduce the activation energy required for fixed carbon combustion of it.