Based on genetic algorithms (GAs), a method of designing a fuzzy logical controller for complex processes is proposed. After a brief overview of GA, the selection of GA's control parameters is discussed for designing MIMO fuzzy control systems. We explained the optimization procedure of the fuzzy rules' selection on a large fuzzy input search space. A double inverted pendulum device is used to test the effectiveness of the design method based on GAs. Not only simulation results are shown in the paper, but also the practical operation results are given.