Abstract: It is difficult to control the temperature of electric－heated reactor by means of single loopcontrol,because the interaction,the very large time constant and nonlinearity.Aimed at thes problem.a newcontroller,namely generalized open-loop decoupling controller is presented and successfully applied to the control of the reactor temperature.It is shown that the presented controller has not only good control perfor-mances but also strong robustness.Key words multivariable system,decoupling control,temperature control