Abstract: To realize innocent treatment of oil sludge char, a lab-scale fluidized bed reactor was employed to study combustion of the oil sludge char in the term of nitrogen oxide emission characteristics at various different temperatures and particle sizes, as well as the reduction in the emission of NO_x by using air-staging combustion technology. According to the results of scanning electron microscope and physical adsorption analyses of oil sludge char, the surface structure of the sludge char is dense and its pores are sparse, which is not conducive to the full combustion of organic matter inside. The combustion experiments of oil sludge char show that the generated NO_x is mainly from coke-N and less from volatile-N. Reduction in the combustion temperature and the particle size to a proper extent can not only ensure full combustion of oil sludge char, but also inhibit NO_x emission. When conducting air-staging combustion, by optimizing the excess air ratio, proportion of secondary air and position of secondary air inlet, the NO_x emission is considerably reduced, and meanwhile the generation of fly ash is restrained, and these are beneficial for the ultimate treatment of the flue gas.