Abstract: The problems of slagging and corrosion of heating surface caused by biomass ash formed during the combustion of biomass were concerned. Through analyzing the characteristics of biomass ash, such as the content of element and mineral, physical and chemical properties and ash fusion, the slagging formation process and the mechanism of the heating surface corrosion were discussed. It was found that biomass slagging is caused by the following reasons. Firstly, the forming of the alkali metal sulphates and chloride decreased the fusion point and increased the stickiness in the surface of the fly ash; and then the slagging was formed on the heating surface. In addition, based on the formation of the HCl and Cl₂ during high temperature, the heating surface of the boiler will be corroded owing to Fe reaction with the HCl and Cl₂. According to the analysis of the influence factors on slagging and corrosion including the content of the fuels, temperature in the furnace, materials of the heating surface and so on, it was proposed that some measures such as co-firing of biomass and coal, additives in biomass, biomass fuel washed with water and metal anticorrosion on heating surface, be used to prevent the problems of slagging and corrosion.