Abstract: This paper studies the variant gain control of nonlinear systems,combining the features of variant gain function (-0.255 sin(100πt)) K.Simuli
nk of Matlab6.5 Software is used to establish a simulation model，packaging the subsystem of  ｅ０．３Ｕ and  K,illustrating the effect which K implies on the output system.The simulation output of k is three intervals is different,which shows the features of the non-linear control system.Therefore,in different value intervals,the influence of variant gain k on the output control is analyzed.

Key words: function of variant gain, non-lineal control system；simulation model