To solve the parameter tuning difficulties of auto-disturbance-rejection controllers for induction-motor frequency control system, the paper proposes a parameter optimization method based on variable-metric chaotic strategy. The new scheme could effectively settle the issues of an auto-disturbance-rejection controller, such as the widely dispersed, interactional multi-parameters and difficult of coordinated combination in practical applications. Simulation results indicate the rationality and validity of the scheme above-mentioned.