To obtain the optimal design parameters of the strap-on scheme for the new generation of high-thrust strap-on launch vehicle, an optimization design and analysis method for the hyper-static strap-on load trans-path is performed. PATRAN command language (PCL) is used to construct a parameterization model and perform simulation analysis for the hyper-static strap-on launch vehicle. The Latin hypercube method is used to conduct sensitivity analysis for the design parameters as well. Based on the obove, the combination optimization strategy, containing multi-objective particle swarm (MOPSO) and sequence quadratic programming (SQP), is proposed to achieve efficient optimization for the strap-on attachment equipment and structural loads of boosters. The results show that the combinational optimization strategy, which could decrease the main strap-on linkage structural loads by approximately 30%, is better than a global or a local optimization algorithm to be used only. The research will provide reference for the optimization design of strap-on scheme on the new-generation launch vehicle.