Fermentation temperature is instable in the northern winter which is the bottleneck of biogas system. In order to solve this problem, a heating equipment which was a hot water heater with heat pipe with gas heating used for biogas system was developed. The distance of the heating side with heat pipe from gas stove hole, flow rate of the burning gas and average water temperature were chosen as experimental parameters. The conditions of this processing technology were optimized by the index of thermal efficiency of hot heater. The result showed that the thermal efficiency of the hot water heater reached the maximum value of 63.47% when the distance of the heating side with heat pipe from gas stove hole was 21.5cm, the flow rate of the liquefied petroleum gas was 1.01kg/h and the average water temperature was 35~45℃.