A mathematical model for a two-stage pressure reducing valve connected to a constant pressure supply circuit and a resistance type hydraulic load has been developed. This model can be used for obtaining an optimum design for this kind of valve. A commercial valve (Rivett Model P88-37-93-3/8″) was tested for experimental verification of the model. Computer programs were used to simulate the static and dynamic operation of the valve. Both simulation results and experimental data showed decreases in the reduced pressure drop at high flow rates and fast reduced pressure response to a step input. The speed of response was found to depend on the damping at the poppet stage.