Abstract: Objective The coking problem of biomass in fluidized bed combustion process was studied, and the influence of potassium salt form and content on the sintering and melting characteristics of biomass ash was analyzed.Methods The sintering and melting characteristics and the mineral transformation law of synthetic biomass ash were analyzed by experiments with scanning electron microscope coupled energy dispersive spectrometer, X-ray diffractometer,X-ray fluorescence, and FactSage thermodynamic calculation software. Results In the typical operating temperature range of 750-950 ℃, the sintering and melting degree of synthetic biomass ash aggravates with the increase of temperature and potassium salt mass fraction. In addition, the effects of different forms of potassium salt on the sintering and melting characteristics of biomass synthetic ash are also significantly different. When the potassium salt is in the form of K2CO3,the liquid phase in the synthetic ash could reach up to 34.36%, leading consequently to severe sintering of the ash.When the potassium salt is in the form of KCl, most of K and Cl elements escape at 750-850 ℃, and the sintering degree of synthetic ash is weakened in comparison with the K2CO3situation. When the potassium salt is in the form of K2SO4, the liquid phase in the synthetic ash is the least, and the sintering and melting degree is also the weakest. ConclusionChanging the form of potassium salt and controlling the temperature of fluidized bed are expected to alleviate the coking problem of biomass in fluidized bed combustion.