Spatial Information Grid is the next generation of space infrastructure, which is integrating Web services, grid computing, and other leading-edge technology. Distribution of is an important feature of the Spatial Information Grid. Equipments and resources, such as the high-performance and computing power of the different types of computers and databases, compose the high-performance grid, and are distributed in different geographical location, across the broader geographic scope. To allow users to access to spatial information faster and better, data replication techniques are used to copy the data to the different sites in where users can access the information easily in the Spatial Information Grid. In this way, it can reduce the response time and enhance the robustness of the distributed computing. The author discusses the data replication technology which is used in Spatial Information Grid and studies the algorithm of the replica selection. This paper mainly include the following :This paper introduces the concept of Spatial Information Grid, architecture and Research Status and analysises the key technical of the replication technology in Spatial Information Grid. It also presents process of replica services in the Spatial Information Grid.The algorithm of the replica selection was studied in this paper. The author used the improved simulated annealing algorithm was used in choosing the optimal path of accessing the each replica and then the optimal replica was selected to match the probability. In this way,it can minimize cost in archieving the jobs and improve the system as a whole benefits.