The invention discloses a thermal desorption based soil repair heat source system. The system comprises an ethyl alcohol liquid supply device, an ethyl alcohol steam generator and a combustion heatingfurnace body; the ethyl alcohol outlet end of the ethyl alcohol liquid supply device is connected with the ethyl alcohol inlet end of the ethyl alcohol steam generator through an ethyl alcohol supplypipe; the ethyl alcohol steam outlet end of the ethyl alcohol steam generator is communicated with an ethyl alcohol steam guiding out pipe; by controlling the flow of liquid flowing from the ethyl alcohol supply pipe in real time and adjusting the heating power of an electric heating wire in real time, ethyl alcohol liquid is just gasified completely when flowing to the lower end of a spiral slope surface along an ethyl alcohol gasification spiral slope, and heat emitted by the slope surface of the whole ethyl alcohol gasification spiral slope is sufficiently utilized.