Compared with traditional distributed system, the cosupply system has high energy saving rate and less environmental pollution, which is one of the important ways to achieve the goal of energy saving and emission reduction. The primary energy utilization efficiency, energy saving rate, power supply efficiency, power supply coal consumption and cost payback period of the combined cooling and power system are calculated and analyzed through a natural gas combined cooling and power project, and a comparsion with other system is made. It states that the combined cooling and power system has higher primary energy utilization efficiency, and lower coal consumption than power plant, which shows an obviouse the energy saving effect. According to the sensitivity analysis of the payback period, the economic income and investment recovery period are greatly affected by the natural gas price.When the threshold is exceeded, the economy is not as good as that of the distributed system. So the local natural gas price and electricity price should be well considered.