In order to maintain the water flux of reverse osmosis membrane treatment at low temperature，now raw water heating device is always set in water treatment system of the power plant. It describes the conventional steam heating scheme and the optimized water-water heating scheme of reverse osmosis influent in a gas turbine power plant, studying the optimization reason，emphatically analyzing the feasibility and advantage of water-water heating scheme, introducing the system design and equipment configuration of optimized scheme. By comparing to the investment costs and benefit of the two schemes, it is concluded that the the optimized heating scheme has more economic benefits and can be popularized within certain limits.