The invention discloses a random verification code that comprises a random text generation module, a verification code module, a business logic module, a database and the like. According to the invention, user access information is obtained through a system, including user information and access information, such as access address, access time and other dimension parameters. Based on the verification code container selection algorithm, a random text is extracted in the database, verification code characters are then specified in the random text through the verification code module, and a user is notified of verification code selection rules and reminded of the corresponding verification code. If the user is notified of the selection rules, the user only needs to select and input the corresponding verification code to verify. By containing the verification code in the random text, the random verification code improves the security of the verification code system and effectively prevents automatic identification of a machine program.