A novel multiobjective optimization algorithm for the parameters decision problem is proposed to find the best design project of high-speed compound helicopter. The new algorithm can improve reliability and robust of the result using improved genetic algorithm based on design for 6σ. The aerodynamic performances of high-speed compound helicopter are computed through numerical integral method based on blade element theory and dynamic inflow theory, so the constraint functions and the preliminary objective functions are built. Design for 6σ is combined into improved genetic algorithm and final objective functions are established. The multiobjective optimization design for high-speed compound helicopter general parameters is carried out with given payload. Pareto solution set is gained through the optimization method, and result indicates that the method is feasible and efficient.