The invention discloses an annual power balance measuring and calculating method, device and apparatus. The method comprises the steps of obtaining basic data; wherein the basic data comprises load historical data, a power transmission and reception plan, operation historical data of a first power supply, operation historical data of a second power supply and an overhaul plan; according to the operation historical data of the first power supply and the operation historical data of the second power supply, converting the adjustable output of the first power supply into equivalent adjustable output expressed by the installed capacity of the second power supply; calculating the total adjustable output according to the equivalent adjustable output of the first power supply, the operation historical data of the second power supply and the maintenance plan; evaluating the maximum load demand according to the load historical data and the power transmission and reception plan; and carrying outannual electric power balance measurement and calculation according to the maximum load demand and the total adjustable output. According to the scheme, the invention does not depend on meteorological prediction data, wind power can be converted into thermal power with the same reliability through historical data mining, and scientific evaluation of the power generation capacity of the method isachieved.