As the economy developed area, there is an urgent need to develop clean energy in Jiangsu province, such as natural gas power generation. In order to promote the healthy and orderly development of gas power generation industry, this paper researched the production & operation situation of four 9F gas-steam combined cycle power plants in Jiangsu province, summarized the situation of generation cost from 2009 to 2011, and analyzed the impact factor of generation cost. The research results show that the gas price, utilization hours and unit operation mode have important influence on the generation cost. Finally, this paper suggests the methods for reducing generation cost, such as increasing the generating equipment availability and improving unit operation mode.