The invention discloses a negative selection intrusion detection method based on the variable self-body radius, and the method is mainly used for solving the problem of poor detection effect because the self-body space formed by setting a fixed autologous radius can not be better covered in the traditional method. The negative selection intrusion detection method is implemented through the following steps: 1) pretreating a KDD (Knowledge Discovery In Database) 99data set; 2) selecting parts of normal data from the data set to serve as an self-body so as to form a self-body set; 3) randomly generating a foreign body, and setting the variable self-body radius for all self-bodies by utilizing a distance characteristic between the self-body and the generated foreign body; (4) training a detector set D; and (5) detecting the test data by use of the detector set D so as to judge whether the test data is normal or abnormal. The negative selection intrusion detection method based on the variable self-body radius has the advantages of high positive detection rate and low misinformation rate, the effect of the negative selection intrusion detection method can be effectively improved under the condition that the self-body data amount is small, the negative selection intrusion detection method is used for identifying the abnormal network data, and ensuring the network safety.