Abstract: With the optimization platform of three-dimensional(3-D) design,the optimization design was carried out for rotor 2 of a two stage counter-rotating compressor in multistage environment based on the methods such as: three-dimensional Navier-Stokes(N-S) flow computation,blade section parameterization,artificial neural networks and genetic algorithm.The optimization objective is to maximize the isentropic efficiency while the mass flow and total pressure ratio are controlled.Numerical results show that efficiency is increased by 1.5% at design point after optimization of rotor 2.The gain in aerodynamic performance is largely attributable to the reduction of losses due to flow separation in suction side,as observed through flow field analysis.