The invention discloses a method and apparatus for detecting a webpage back door. The method comprises the following steps: determining a weight of an access file according to a preset condition, wherein the access file is used for accessing a webpage; judging whether the weight is greater than or equal to a preset threshold; when it is judged that the weight is greater than or equal to the preset threshold, determining that the access file is the webpage back door. By adoption of the method and apparatus disclosed by the invention, the technical problem that the accuracy of detecting the deformed webpage back door is relatively low in related art is solved.