The present disclosure discloses a method, apparatus, and server for user verification to store a plurality of pictures in a database and define a plurality of rotational directions. The method includes: when receiving from a client a request for a checkcode, rotating a picture retrieved from a database according to a defined rotational direction; after storing a correlation between an identification of the client and the rotational direction of the retrieved picture, outputting the rotated picture to the client; receiving a rotational direction of the picture from the client; finding the stored correlation between the identification of the client and the stored rotational direction of the retrieved picture according to the identification of the client; determining whether or not the rotational direction of the picture returned from the client matches the stored rotational direction. If they match, user verification is passed; otherwise, the user verification is failed. The large number of pictures in the database makes it difficult for enumeration. In addition, by using the rotational direction as identification information to verify user, the safety and accuracy of user verification can be enhanced.