—Instant Messaging (IM) service is a killer application in the Internet. Due to the problem of IM spam (SPIM), building an effective anti-spim method is an important research topic. At present, most of anti-spim solutions are based on email-spam prevention techniques, which are not directly applicable to anti-spim. In this paper, we present a new anti-spim method SpimRank, which integrates trust and reputation mechanisms with black-list technique. SpimRank also tracks user’s historical action to deal with spim attacks in nearly real time, which is applicable to IM environment. Keywords- Instant Messaging, SPIM, Reputation