A reference scheme of a multiple energy complementation system is of great importance of Chongming's energy system development. In this paper, four feasible scenarios which are distinguished by energy supply forms have been discussed based on RETScreen software. Economic analysis as well as the renewable sources penetration was taken into account. The outcome of equipment size optimization of each subsystem was summarized and the comparison between different scenarios was afterwards conducted in order to provide some thoughtful comments for the future energy system construction. Results indicate that the introduction of natural gas based CHP system and biomass system is a necessity for covering the energy demand and minimizing the energy import. The CHP scenario achieves the most annual balance (0.3272 billion yuan) and net present value (2.556 billion yuan) and cuts down the GHG emission by 1.978 Mt per year. Moreover, the net present value of the proposed energy system is sensitive to the variation in energy policy. When the financial aids fluctuates by 50%, the net present value can change in the range from 60% to 70%. However, even when the policy is extremely unfavorable, the economical profit of CHP scenario is still obvious. (C) 2017 Elsevier Ltd. All rights reserved.