Abstract: In order to make the implementation of the load-balance more effectively in distributed system, in this paper, associating with the self-designed distributed database server system extracting the three-layer management-frame of the distributed redundant system and studying the objective description and definition of load index, the active load balancing idea is introduced into the system and a load balancing model based on mobile agent is presented. Finally, the performance of the system is also analyzed. Analysis indicates that the model of MMA has the advantages of little cost, and being more intelligent and more accurate in scoring the load indexes than some existing systems.