The present disclosure discloses a method, server, and system for automatically rating the reputation of a web site, wherein the method comprises: when a web address of the web site is triggered and intercepted, detecting whether the web address of the web site is a malicious web address or a non-malicious web address; making statistics of the number of malicious and non-malicious visits to the web addresses under the web site during a predefined time period and saving the statistics to a database; and reading records from the database and calculating an average reputation of the web site by weighting the statistics of visiting the web site during the predefined time period and history statistics. The present disclosure is able to mark the reputation of a web site in time and efficiently, thus improving the security of using the network.