Abstract: It is a trend that the proporational control valve subsititute for servo valve in most field of engineering applications.This paper introduces a digital control-amplifier for electro-hydrolic proporational direction throttle valve,which is aggregatied with the valve controlal system.Its core is the system of Intel 8098 microcontroler.Subsitituting for the appropriative proporational amplifiers with the digital control amplifiers.It not only simplifies the valve controlal system,raise the reliability,but also raises the economity and agility of the controlal system.The digitalcontrol amplifiers make an foundation for popularizing aplication.The hardware、software and experimental results are presented in thispaper.