The paper proposes a control design approach based on a multipoint linearization method for linear electro-hydraulic servo systems. The nonlinear model - which includes the nonlinearities of friction forces, valve dynamics, oil compressibility and load influence - is developed by means of the associated differential equations. Based on some mathematical transformations and approximations, the model of servo system is reduced to a family of linear systems which can approximate the behavior of system on the whole operational domain. These models are used to design an optimal controller which modifies online the feedback control parameters. Simulation and experimental results are provided to show the effectiveness of approach.