The system of continuous stirred tank reactors is converted to an uncertain linear system with structured time-varying uncertainties.Based on the type-Ⅱ fuzzy control principle,the controller is designed to stably control the nonlinear system of continuous stirred tank reactors with parameter uncertainty.The results of simulation show that this type-Ⅱ fuzzy controller could stably control the CSTR which has the characteristics of time-varying,time-delaying and parameter uncertainties in the unstable operating point.