Space solar power system (SSPS) is a grand space engineering, in which solar power is massively collected and converted in space, and the electric energy is transmitted to the ground grid by wireless mode. The economic feasibility of SSPS is one of main factors determining whether it can develop on a large scale. Based on multi-rotary solar power satellite(MR-SPS) scheme, a whole life cycle phase division and a cost analysis flow for SSPS are proposed. The preliminary analysis shows that the total cost of SSPS is about 2 500 billion RMB, and corresponding to the life cycle generation of 240 billion degree electricity, the cost of unit electricity is about RMB 1 yuan.