Abstract: In order to reduce the production cost and the emission of CO₂, the n(H₂)/n(CO) ratio can be adjusted by combining the coal water slurry with the natural gas. The competitive ability of each reaction in the co-gasification process was analyzed from the point of view of thermodynamics. The process was simulated by Aspen Plus software, and the effect of oxygen inlet flow rate and natural gas inlet flow rate on the outlet temperature, mole composition of gas, mole fraction of syngas and H₂/CO were analyzed. The export parameters under the different inlet flow rates were calculated. Through screening these data, natural gas and oxygen inlet flow rates were obtained while the gasification chamber outlet temperature was 1 340-1 360 ℃, the ratio of n(H₂)/n(CO) was more than 1.15, and synthetic gas mole fraction was greater than 0.72.