Abstract: This article introduces the data fusion theory into the intrusion detection process，proposes an intrusion detection system model based on the data fusion，and has applied the multi- Agent technology in the system model realization process，enable the entire model having the good extension.In the data fusion process of clustering，merging and associating this article applies the D-S evidence theory，solves the problems of warning onrush，high false reporting rate，inferior question between the warning association which existed in the current intrusion detection system，enhances the detection performance of the distributing intrusion detection system.