Abstract: To achieve the clean and efficient utilization of the coal gasification fly ash,experimental studies which adopted advanced selfpreheating combustion technology were carried out on a 30 kW preheating flameless combustion test rig for solid carbon-based fuel. FuelN transformation and NO_x emission characteristics from fine ash of bituminous coal gasification fly ash under different preheating temperatures and primary air equivalence ratio were discussed. The results show that the coal gasification fly ash can achieve stable flameless combustion on this experimental system. The combustion characteristics of coal gasification fly ash are greatly improved after preheating. Almost all volatile-N is removed in advance under the strong reducing atmosphere in the self-preheated burner,and is mainly converted to three nitrogen-containing substances: N_2,NH_3 and HCN. Thus char-N is the main source of NO_x emission in subsequent combustion. During the preheating progress,preheating temperature has an obvious effect on the conversion of fuel-N to N_2,while the primary air equivalence ratio mainly affects the conversion rate of fuel-N to N_2,NH_3 and the nitrogen precipitation from char-N. The effects of preheating temperature and primary air equivalence ratio of preheated burner on NO_x emission concentration and conversion rate of fuel-N to NO_x are obviously different. The concentration of NO_x emission and conversion rate of fuel-N to NO_x both reach the lowest value when the preheating temperature is 902 ℃ and the primary air equivalence ratio of preheated burner is 0.45,which are 83.02 mg/m~3 (6% O_2) and 5.94%,respectively.