The combustion condition of the burner was calculated by the eddy dissipation model and the non-premixed combustion model respectively. The results showed that when the velocity of coal gas injection increases or the velocity of air injection decreased, each consumption rate of C_xH_y, CO and H₂ reduced, and each production rate of CO₂ and H₂O also reduced, and the length of the flame adds. The area of the highest temperature calculated by the eddy dissipation model was more concentrated than that by non-premixed combustion model. With the velocity of coal gas injection increasing, the area of backflow region calculated by eddy dissipation model reduced, the velocity of air injection increasing, the area of backflow region increasing slightly. Both the velocities change of coal gas injection and air injection had no influence on the area of backflow region calculated by non-premixed model. Comparing the calculation results of two models, the flow field calculated by eddy dissipation model was more accurate, the temperature field calculated by non-premixed model was more accurate instead.