In order to realize the waste biogas recycled as reburning fuel in industrial boilers aims to reduce nitrogen oxides （NO_x） high efficiency, which can achieve resource recovery and NOx emission reduction. Characteristics of industrial boiler bed and furnace were simulated by combining FLIC and FLUENT software, and the effects of CH₄/NO molar ratio, biogas dilution and biogas nozzles arrangement on in-furnace NO_x emission were investigated. The results showed that the CH₄/NO molar ratio and the degree of mixing between the two were the main factors affecting the reduction of NO_x, and NO_x reduction efficiency increased with CH₄/NO molar ratio and biogas dilution ratio increasing in general. When the CH₄/NO molar ratio was small, the dominant factor influencing NO_x reduction efficiency was the mixture degree of them. When biogas was diluted to a certain degree, which could guarantee possessing sufficient momentum to mix well with the main flow, the dominant factor influencing NO_x reduction efficiency was CH₄/NO molar ratio. At the same time, increasing of biogas dilution ratio was beneficial to reduce the loss of gas incomplete combustion. To realize of NOx high efficiency reduction, the biomass nozzles should be arranged at the front wall, and the position should not be too low. This paper could provide some reference of biogas for industrial boilers combustion and NO_x reduction.