Abstract: By analyzing the effects of coal quality on operating cost of coal-fired power plants, an evaluation model was established for calculating the comprehensive use cost of fuel coal. Based on fuzzy association rule data mining technology, an algorithm was proposed to determine the correlations between the coal quality and the power plant operating cost, including the coal transportation cost, the anti-pollution cost, the coal purchasing cost, and the equipment maintenance cost, while a method put forward for decision of the most economical coal. On the basis of 3 years operating data of a power plant, an analysis has been carried out on comprehensive cost of the 4 coals in the pre-procurement plan, after which the most economical coal is determined. Results show that not only the production processes of power plant, but also the coal price and coal quality should be considered in determination of the coal procurement policy. It is not always more economical to burn low-price low-quality coal than high-price high-quality coal. In above case, coal No.2 is finally determined as the most economical one.