An advertisement filtering method and device. The method comprises: access a web page by using a browser, acquire a selector of an advertisement element according to a domain name of the web page, and add a rule statement for hiding the advertisement element after the selector to generate a CSS style of a specific category (S10); inject the CSS style of the specific category into the browser (S11); set a cascading priority of the CSS style of the specific category to a highest cascading priority (S12); and the browser performs cascading on the CSS styles according to an order of the cascading priority of the CSS style to enable the CSS style of the specific category to take effect (S13). In this way, in a case in which an author uses a counter advertisement filtering method, an advertisement from the author can still be effectively filtered.