With the development of the grid technology

for quick response to the requirement of data application

the concept of data grid has appeared after computing grid. The query function is used very frequently in the database application

the same to the grid environment. It appears frequently that composing the database which distribute in various computer nodes to make a virtual database dynamically to finish a query because every database only includes a part of the information. This paper detailed research the question that how to finish the query and shorten the response time under the grid of heterogeneity of the nodes and the widely various communication speed between the nodes. It has important significance for the further research and development of grid database.