There are two issues involved in designing the architectures of engineering database management systems. The first is which kind of client/server structure is to be employed to make a proper distribution of functions between client and server. And the second is which kind of concurrency control algorithm is to be used to guarantee the consistency of the caching data at clients. Three client/server architectures(i.e. Object-server, Page-server, File-server) are dicussed, the differences among them are designated, the advantages and disadvantages of each are pointed out in this paper. The various concurrency control algorithms for cache consistency are also studied. Finally, the architecture of OSCAR, an engineering database management system, is introduced.