According to the experience having telecommunication networking and running management, the model of community access network was summarized and abstracted; It is analyzed that the prime cost about networking, running in the community, The cover cost, equipment port cost, user access cost, service cost, pay cost to other operator were calculated according to the project norm and current price of community access network; The investment payback period was aimed. The analysis mode of the model of community access network was set up. And the investment payback period was calculated with the various model; Based on the method of elastic function, The sensitiveness was analyzed with the investment payback period to the parameter separately, such as occupation rate, service cost, cover cost, equipment port cost, etc.