The ever-rising complexity of operating system and communication networks has resulted in increased difficulty in detecting intrusions.So applying immune mechanism of human body to construct next generation intrusion detection becomes a new research focus.This paper presents a novel method to encode the antibody-antigen.And An generic algorithm based on niche technology of share function for generating diverse antibody is provided.In order to verify the validity of the algorithm

two evaluation function are suggested.The experimental results reveal that the algorithm has much to offer to keep population's diversity during evolution.