In this paper,for the dynamic theory of the P2DR security model,an association rule mining algorithm is applied to the intrusion detection technology,and  the Apriori algorithm improved.The improved algorithm greatly compresses the number of association rules,and effectively reduces the result set number of rules.The experimental results show that the number of association rules can be effectively compressed,and the efficiency for network data mining is improved .This algorithm effectively decreases the misinformation rate and the rate of fail to report an invasion behavior in intrusion detection systems.