Abstract: Semi-coke is the product of low-rank coal pyrolysis at low temperature. The price of pulverized semi-coke is lower than that of bituminous coal which is the commonly used in industrial pulverized coal boiler. If semi-coke can be used as the fuel of industrial pulverized coal boiler,the applicable fuel range of the coal-fired industrial boiler will be widen. Besides,the market competitiveness of coal-fired industrial boiler can be enhanced. Because of the low volatile content and a high fixed carbon content,semi-coke needs a higher temperature for ignition and steady combusiton. What's more,the decrease of NO_xemission is a also a technical problem. The NO_x emission properties of semi-coke air-staged combustion was studied in two-stage drop-tube furnace to realize steady combustion in pulverized coal industrial boiler and low NO_xemission of semi-coke. In this paper,the NO_xemission law of semi coke air non-staged combustion was studied.The influence of fuel-rich zone temperature( 1 000-1 400 ℃) and excess air coefficient( 1.0-1.3) were explored to give a comparison with the following air-staged combustion experiment. In semi-coke air-staged combustion experiment,the influence of the fuel-rich zone temperature( 1 000-1 400 ℃) and the ratio of secondary air( 0.4-0.8) were explored. Besides,the burn-out rate,NO_x decrement rate and microscopic pore structure and morphology of air-graded combustion ash were analyzed to reach a comprehensive conclusion. It can be concluded from the non-staged combustion experiment that under the condition of air non staged combustion,and when the ratio of exhaust air to air distribution is 0,the NO_xemission increases rapidly with the fuel-rich zone temperature increasing. When the excess air coefficient increases,the NO_xemission increases rapidly first,and then the increase becomes slowly when excess air coefficient is over 1.15.It can be concluded from the air-staged combustion experiment that when the ratio of secondary air changes from high to low under the same temperature of the main combustion zone,the NO_xemission shows a trend of rapid decline and slow recovery,and the burnout first increases rapidly and then tends to be gentle. The optimal ratio of secondary air is 0.56,when the NO_xemission concentration is under120 mg/m3,and the burn-out rate and the decrease rate of NO_xare all at a high value.