The invention is applied to the technical field of information security, and provides a watermark generation method, a client side and a server. The method includes the steps of sending logging information to the server so as to enable the server to verify the identity of a user on the client side according to the logging information, generating unique identification data corresponding to the user on the client side, and sending the unique identification data corresponding to the user on the client side to the client side when verification of the identity of the user on the client side passes; receiving the unique identification data sent by the server; generating watermarks according to the unique identification data and superimposing the watermarks to multimedia data to be played. The identity of a publisher of the multimedia data can be verified through the watermarks in the multimedia data, the situation that the multimedia data are obtained to carry out infringement through recording or shooing and other non-contact modes is achieved, and a spreading source can be effectively tracked.