NOVELTY - A multifunctional four season high temperature solar fermentation methane tank comprises a methane tank and a fermentation tank, a water pressure chamber connected to the fermentation tank and a feeding port, and a gas-guide tube; where the circulating loop is set with a water pump; and the water pump is controlled by an automatic controller comprising a relay switch connected to the water pump power wire, a temperature sensor mounted in the fermentation tank, a signal processing circuit connected to the relay switch and the temperature sensor, and a relay switch starting circuit.    USE - The multifunctional four season high temperature solar fermentation methane tank is useful for industrial and commercial applications.    ADVANTAGE - In utilizing the multifunctional four season high temperature solar fermentation methane tank, the insulating layer is increased which avoids heat loss and uses residue heat after combusting methane. Moreover, the tank can achieve stable and efficient methane production in cold area with great temperature change.    DETAILED DESCRIPTION - A multifunctional four season high temperature solar fermentation methane tank comprises a methane tank and a fermentation tank, a water pressure chamber connected to the fermentation tank and a feeding port, and a gas-guide tube; where the methane tank comprises two layers which form an interlay for passing through circulating water, a solar water heater, and an insulating box that is additionally arranged outside the water heater, and is connected to the interlayer of the fermentation tank and the solar water heater through the water introducing pipeline, which forms a water circulating loop; the circulating loop is set with a water pump; and the water pump is controlled by an automatic controller comprising a relay switch connected to the water pump power wire, a temperature sensor mounted in the fermentation tank, a signal processing circuit connected to the relay switch and the temperature sensor, and a relay switch starting circuit.    DESCRIPTION OF DRAWING(S) - The drawing shows a schematic diagram of the multifunctional four season high temperature solar fermentation methane tank.