Abstract: Introduction The problem of cavitation and reduction of output of water ring vacuum pump that existing in the operation of the pumps in power plant has been the prime focus of project owners. Method The working principle of vacuum pump was analyzed, the reason of the problem mentioned above was presented and the scheme solving this problem was proposed. Result Results show that the optimized design scheme has the advantages of increasing the output and reducing the energy consumed of vacuum pump, improving the operation security of vacuum pump and economic efficiency of power plant. Conclusion Thus,this work provides some guidance for the design of the cooling water system for working liquid of water ring vacuum pump in various types of power plant.