A design method of optimized Fractional Order Internal Model Controller(FOIMC)is proposed for complex systems. A Seeker Optimization Algorithm(SOA)with chaos operators is used to reduce and simplify the system model.Based on this above, a new FOIMC is designed and the optimization parameters tuning is achieved. The simulation results show that the reduction mode approximate the original system with a good accuracy, and the designed controller can provide a good dynamic performance and a better robustness ag...