This paper reports the modeling, design, and dynamic simulation of a piezoelectrically-driven microfabricated valve for high frequency regulation of high pressure fluid flows. The enabling concept of the valve is the ability to convert the small displacement of a piezoelectric element into a large valve cap stroke through the use of a hydraulic fluid, while maintaining high force capability. The paper focuses on the development of a sytematic procedure to arrive at a geometric valve design for given performance requirements. Modeling of the non-linear large deflection behavior of the valve membrane and design of this structure to maintain stresses below critical levels are discussed. Design of the piezoelectric material drive portion of the valve to create a stiffness match with the valve membrane and external hydraulic system is detailed. In addition, this paper presents a dynamic simulation of the active valve, including effects such as valve cap dynamics and fluid damping, that allow for understanding and prediction of valve performance under various loading conditions.