A method of establishing a main machine equipment database of a thermal power plant based on life-cycle cost comprises the steps of a, forming a sub-equipment list for boilers and steam turbines according to the contents of a thermal power plant main machine equipment purchase contract; b, disintegrating life-cycle cost of main machine equipment according to a life-cycle cost model in conjunction with actual maintenance and management characteristics of the thermal power plant, and disintegrating the life-cycle cost of each device to form a life-cycle cost list of key devices; c, investigating basic statistical data of the thermal power plant, subjecting investigation results under different design conditions to classification and conversion, and establishing life-cycle database systems for thermal power plant main machine equipment of different types; d, summarizing and analyzing the same type of main machine equipment database systems by different manufacturers so as to form basic input parameters applicable to evaluating the life-cycle costs of this type of main machine equipment of each manufacturer, and using the parameters to evaluate and analyze life-cycle cost of this type of main machine equipment by the manufacturer.