Abstract: new multivariable robust self-tuning decoupling controller is presented.Since a new control1aw is used,the unmodelled dvnamics and u nmearsurable disturbances are overcomed effectively. In the caseof existing stronger unmodelled dynamics and bounded unmearsurable disturbances,the stability of the system is not only assured, but also the rubust selftuning decoupling can be realized.Anew method of normalization coefficients and width of deadzone is used.It does not effect system tracking character,Finally,therobustness analysis and simulation results of the presented algorithm are also given.