The invention provides a digital video content security authentication method. The method comprises a secret information embedding steps of selectively modifying a pixel grayscale value for each frame image in a digital video, thereby finishing embedding one byte of secrete information; and a secret information extraction and video authentication step of carrying out secret information extraction from the digital video in which the secret information is embedded according to a key, thereby realizing digital video content security authentication. The invention also provides a digital video content security authentication system. According to the technical scheme of the method and the system, the authentication security is improved on the basis of not influencing user experience.