The control problem under the condition of uncertainty is an important subject of modern control field.In most control problems,the actual control object and mathematical model for the controller design are always present differences.These differences come from the object parameter uncertainty and timevarying,etc.Mill hydraulic position servo system is the complex nonlinear control system with parameter uncertainty and lots disturbance factors.There is biggish error bewteen the established model and the actual object.In order to eliminate the steadystate error caused by this kind of model error,parallel integral compensation,gain integral compensation,online identification selfcalibration and dynamic feedback control strategies were built on the basis of source tracing of the steady state error and model correction.The simulation results in comparsion show that the dynamic feedback algorithm has the advantages of both dynamic and static performance index.