Nowadays, grid systems are vital technology for programs running with high performance and problems solving with large-scale in scientific, engineering and business. In grid systems, heterogeneous computational resources and data should be shared between independent organizations that are scatter geographically. A data grid is a kind of grid types that make relations computational and storage resources. Data replication is an efficient way in data grid to obtain high performance and high availability by saving numerous replicas in different locations e.g. grid sites. In this research, we propose a new architecture for dynamic Group data replication. In our architecture, we added two components to OptorSim architecture: Group Replication Management component (GRM) and Management of Popular Files Group component (MPFG). OptorSim developed by European Data Grid projects for evaluate replication algorithm. By using this architecture, popular files group will be replicated in grid sites at the end of each predefined time interval.