A proximity box based detection algorithm is presented to improve the efficiency of proximity detecting in distributed environment.Proximity detection is to find each pair of friends such that the distance between them is within a given threshold.Servers in Location-Based Services are likely to be the bottlenecks in large scale proximity detecting

therefore

the state-art-of proximity detection methods are designed with the goal to reduce the server load.In this paper

we propose a detecting method based on proximity box instead of the Euclidean distance or the shorted distance

thereby improving the processing efficiency of the system.At user client

an adaptive method with the road map information is introduced to predicting the users security moving zone for reducing the message exchange between the client and server.The detailed steps of the proximity detection algorithm are given and approaches to deal with suspected proximity user are discussed.An indexing algorithm for moving users and proximity relations between friends is also discussed.The experimental results indicate the algorithm is effective in a real city map.The results also prove that proposed index algorithm can significantly improve the overall efficiency of the system.