Biogas is one kind of the renewable energy which is suitable to develop in rural areas. One of the key concerns of biogas plants is keeping anaerobic digestion at a certain temperature in an economically sustainable and environmentally friendly manner. Consequently, in order to increase the total comparatively low quantity of biogas production in the cold weather, heating system should be integrated. This paper analyses the economic performance of anaerobic digestion of a given plant with the same heat load in terms of heating technique. And the comparison among various parameters for heating systems demonstrated that the crucial factors including initial investment, operation cost, net present value (NPV), IRR, benefit-cost (B/C), discounted payback period of investment (P), primary energy consumption behave utter differently. The initial investment in the solar energy heating method turns out large than others; the net annual benefit and B/C in solar energy heating is higher than the other six; Operating cost, P and PEC in electric heater heating are all surpass the rest of the methods. After discussing the advantages and disadvantages of the three major aspects, including technique, economic and environment, suggestion is made for each type of plant with the suitable heating method. GSHP heating system is profitable for the promotion of middle scale biogas plants with its IRR=20, B/C=6.6, P=3.9.