Abstract: Bayes filtering has a dominant place in the area of spam filtering for its strong categorization and high precision. Artificial immune system has become a new embranchment in computing intelligence for its good self-learning, self-adaptability, and robusticity. This paper analyzes the basic principle of Bayes and artificial immune systems, proposes a hybrid spam filtering algorithm based on Bayes and artificial immune system, and then designs and develops the spam filtering system based on this algorithm. It is proved that this system is effective to filter spam in English and Chinese e-mail corpus.