The invention relates to a heat supply system of a thermal power plant, in particular to a heat supply system and method suitable for thermal power plant peak adjustment. The system comprises a powergeneration system and a heat supply network, wherein the power generation system is used for converting heat energy into electric energy, and outputting partial residual heat energy to the heat supplynetwork through a pipeline; the heat supply network comprises a circulation loop; and a heat exchanger, at least one heat storage system and at least one first-grade user side are arranged on the circulation loop of the heat supply network. The heat supply network exchanges heat with the residual heat energy of the power generation system through the heat exchanger; the heat storage system is parallelly connected onto the circulation loop of the heat supply network, and is used for storing the heat energy at the heat supply trough period and releasing the heat energy at the heat supply peak time; and the first-grade user side is distributed on the heat supply network, and is used for utilizing heat energy in the heat supply network and returning the heat energy to the heat supply network.The heat supply system and method suitable for thermal power plant peak adjustment provided by the invention aims to solve the problems that the heat supply system carries out peak-load shifting so as to cause uneven cold and hot at far and near ends under the situations with the quick increase of a heat supply area and the great demand of heat supply.