Abstract: A mobile agent distributed intrusion detection system(MADIDS) repairing mechanism based on mobile agent is introduced in this paper. MADIDS is special designed for WAN environment. MADIDS Data is calculated by distributed agent at every node. Not only has it carried out a intrusion detection at network range and a well migrate character, but also there is possibility of lowering network bottleneck because of the low cost of network system and host computer resource. Restorability and Invulnerability at every layer of the system has discussed in this paper. Experiment proved that this mechanism is displaying a well performance.