Abstract: A fuzzy logic controller (FLC) of dyeing jig is developed in this paper. The plant is a multi-inputs/multi-outputs nonlinear system with time varying parameters. To deal with the coupling interactions between two control variables, the "principal-subordinate alternate" control strategy is proposed. Considering the nonlinearity and time varying parameters, the "on-line self tuning rules" are employed in the FLC control algorithm. Instead of hydraulic pressure control, the technique of frequency conversion governor (FCG) is applied. The hardware implement of two-input /two-outputs FLC is described and the real-time operating results of dyeing jig are given.