In the process of installating aero-engine rotor blade, the manufacturing errors of blades can lead to the mistuned effects among the blades. Different assembly plans of blades produce different forced vibration responses of the bladed-disk system. It can obtain mistuned frequency difference of blades by a modal test, and then get the mistuned parameters. A 2-DOFs lumped-parameter kinetic model of single sector is built in a mistuned bladed-disk system. Based on the advantage of overall optimization and fast convergence of genetic algorithm, and using the improved nested genetic algorithm, a blade′s optimization assembly scheme of a certain bladed-disk system is proposed for a certain type aero-engine. The scheme can make the maximum amplitude of forced vibration response achieve minimum one or in a smaller range.