The purpose of this paper is to examine the distributed databases and some problems of Grid dealing with the data replication from different points of view. This paper is referred to find out the most efficient commonalities between Data Grid and managed data stored in object-oriented databases. We discuss the features of Distributed Database System (DDBS) such as design, architecture, performance and concurrency control and submit some research that has been carried out in this specific area of Distributed Database System (DDBS). Query optimization, distribution optimization, fragmentation optimization, and joint option to the optimization of Internet are included in our research. Our project design, advantages of its results and examples concerning this topic are presented in this paper.