Abstract: The client/server architecture is a kind of new technology for constructing database systems. Based on the analysis of the features and some shortcomings of the standard client/server architecture,a kind of extended client/server architecture is proposed,which is fit for CAD/CAM application needs（design alone, cooperation with each other, long transaction process, etc.） .Then introduced are the dEDBMS system——a distributed engineering database management system based on the extended client/server architecture, and some key implementation methods.