A method and an apparatus for filtering a uniform resource locator (URL). According to the method, a first category corresponding to a URL connection request can be found in a pre-stored category information table; when the first category conforms to a predetermined URL passing through policy, the URL connection request is allowed to pass through; the URL connection request is forwarded to a corresponding server; a second category corresponding to a URL is determined according to web page content returned by the server; if the second category conforms to the predetermined URL passing through policy, the web page content is sent to a client; if the second category does not conform to the predetermined URL passing through policy, the web page content is blocked. A category to which a URL belongs can be determined in real time, and implementing a function of accurate category filtration.