Abstract: Due to the increasing types of coal supplying to coal-fired power plants and larger portion of low-quality coal,there is a large difference in coal quality between the actual coal and the design coal,which affect the safe and stable operation of boiler.To resolve these problems,investigate the linear additivity of four coal quality indicators such as volatile,sulfur,calorific value and ash fusibility.Evaluate the security and stability of boiler from the coal quality linear additivity of blending coal.The results indicate that the coal blending technology can meet the security demands of boiler in power plants.The indicators such as volatile,sulphur,calorific value of blending coal have linear additive.Blend the coals whose quality is similar,find that there is obvious linear relationship between the blending coal and single coal.The ash fusibility doesn’t have linear additive.To maximize the benefits of coal-fired power plants,it’s necessary to bulid coal blending expert system according to relevant indicators of coal quality.