Abstract: Two methods to improve the steady state accuracy are proposed in this paper.One is multistage control which applies"rough"controller to accelerate the response speed in transient state and uses"precise" controller to improve the steaty state accuracy. By acquiring the time-varing pattern,the othermethod compensates the variation of process to get one fixed out put.The usefulness of thess methods is demonstrated by a simulation example on a two-order process with slowly time-varing parameters. The control system have good steady state feature and strong rijection ability to disturbances.