A combined energy supply system from wind, photovoltaic and solar thermal power having a medium-based thermal storage, comprising: a first medium tank configured to store unheated medium; a second medium tank configured to store heated medium; a wind and photovoltaic power generation equipment configured for power generation; a first heater configured to heat the unheated medium in the first medium tank into the heated medium using power generated by the wind and photovoltaic power generation equipment; a second heater (700, 720) configured to heat the unheated medium output by the first medium tank using a solar heat collector equipment; a heat exchanger configured to heat water to steam using the heated medium outputted by the second medium tank; a steam generator set configured to make the steam drive a steam turbine to generate power; a power transmission equipment connected to the steam generator set; wherein the unheated medium is output from the first medium tank, and heated by the first heater and/or the second heater (700, 720) to be converted into the heated medium which is stored in the second medium tank: the heated medium is then output from the second medium tank into the heat exchanger, and the steam generated by the heat exchanger drives the steam generator set to generate power; wherein an output end of the first medium tank is directly respectively connected to the first heater and the second heater (700, 720) by a pipeline route; and an output end of the second heater (700, 720) is directly respectively connected to the first heater and the second medium tank by a pipeline route, such that the unheated medium is heated by the second heater (700, 720) only without passing through the first heater, or is heated by the first heater only without passing through the second heater (700, 720), or is heated by the second heater (700, 720) first and then the first heater. a first medium tank configured to store unheated medium; a second medium tank configured to store heated medium; a wind and photovoltaic power generation equipment configured for power generation; a first heater configured to heat the unheated medium in the first medium tank into the heated medium using power generated by the wind and photovoltaic power generation equipment; a second heater (700, 720) configured to heat the unheated medium output by the first medium tank using a solar heat collector equipment; a heat exchanger configured to heat water to steam using the heated medium outputted by the second medium tank; a steam generator set configured to make the steam drive a steam turbine to generate power; a power transmission equipment connected to the steam generator set; wherein the unheated medium is output from the first medium tank, and heated by the first heater and/or the second heater (700, 720) to be converted into the heated medium which is stored in the second medium tank: the heated medium is then output from the second medium tank into the heat exchanger, and the steam generated by the heat exchanger drives the steam generator set to generate power; wherein an output end of the first medium tank is directly respectively connected to the first heater and the second heater (700, 720) by a pipeline route; and an output end of the second heater (700, 720) is directly respectively connected to the first heater and the second medium tank by a pipeline route, such that the unheated medium is heated by the second heater (700, 720) only without passing through the first heater, or is heated by the first heater only without passing through the second heater (700, 720), or is heated by the second heater (700, 720) first and then the first heater.