Disclosed is a combined energy supply system of wind, photovoltaic, solar thermal power and medium-based heat storage, capable of storing the energy which would have been “abandoned wind” and “abandoned light” temporarily in the form of heat by medium-based energy storage. Heat is released during peaks in the power grid to generate power, which serves the function of adjusting the peaks in the power grid. With the medium-based energy storage, unstable photovoltaic electric energy can be converted into stable heat energy output when a relatively large fluctuation occurs in wind and photovoltaic power generation, and therefore the stable supply of energy sources can be guaranteed efficiently. Furthermore, a second heater can also be used for heating the low-temperature media outputted by a first medium tank (100), or a third heater is used for heating water in a heat exchanger (500), and therefore the energy storage of the medium or the heating efficiency of the heat exchanger is improved.