The invention provides a closed circulatory phase-change heat supply system for heat and power cogeneration, comprising a boiler, a turbine generator set, a heat accumulator, a heat device, a drain tank, a water storage tank, an economizer and an assorted connection pipe, a water pump, a control valve and the like. A steam pipe of the boiler for steam supply is connected with a steam inlet of the heat accumulator and a steam inlet of the turbine generator set; a steam supply inlet of the heat accumulator and a steam pumping and exhausting outlet of the turbine generator set are respectively connected with a steam inlet of the heat device to ensure that the heat accumulator adjusts the load of a heat supply system; the condensate water of the heat device is collected in the water storage tank after passing through the drain tank via a condensate water pipe; and a water outlet pipe of the water storage tank is connected to the economizer of the boiler, therefore, an enclosed circulatory heat supply system is formed. During the running of the system, the condensate water is not flashed and lost under the saturated high-temperature state, therefore, the heat utilization rate of the system is improved, both the whole system and the running are simplified, and the project investment and the operation cost are reduced.