The invention discloses a method for protecting the copyright of a video demand system, which encrypts the content of the ordered program which is stored in the video demand system, and encrypts demand software operated by the video demand system, further tests the validity of the user terminal of the demand system, if the terminal is legal, the other demand requirements are responded. In the method, since the demand content is encrypted, thereby if the demand programs are leaked out from the demand system, the programs can not be played and watched, the method enables the video content to form a closed system during the transmitting and demand process, which enables the demand quantity to be really and effectively controlled, thereby playing the function of protecting the copyright.