Abstract: PSO is an algorithm based on swarm intelligence optimization and search,has high efficiency,fast convergence．In this paper,it combines with the K-means algorithm for network intrusion detection．Experiment shows that PSO-based K-means algorithm overcomes the shortcoming that the K-means algorithm is sensitive to the initial cluster centers,outliers and noise,easy to fall into local optimal solution．It’s an algorithm with fast convergence and higher detection accuracy.

Key words: Intrusion detection,PSO,K-means algorithm,Detection accuracy