The invention discloses a coal-fired power plant inventory management method based on supply-demand relation, which comprises the following steps of: acquiring the current coal-fired storage amount and coal quality characteristics of a power plant, and acquiring coal quality information of to-be-purchased coal and coal quality characteristic representation vectors of the to-be-purchased coal; determining the fuel coal purchase quantity and the fuel coal consumption; determining a coal blending boundary condition and/or a coal inventory condition in the current fire coal planning time of the power plant; and establishing a fire coal purchasing objective function, and obtaining an optimal solution of the objective function according to the coal blending boundary information and/or purchasinginventory information of the power plant within the current fire coal planning time so as to obtain an inventory fire coal purchasing plan. The invention further discloses a coal-fired power plant inventory management system based on the supply-demand relation. According to the technical scheme, aiming at the situation that the quality and quantity of the coal inventory of the current power plantneed to be effectively balanced, the inventory coal quantity of the coal-fired power plant is dynamically planned, and the normal operation of the power plant can be ensured while the quality and quantity of the coal quantity of the power plant are ensured under a certain economic constraint condition.