The invention discloses a video copy detection method and a system. The method comprises the following steps: an inquired video and a detected video are converted to digital videos with the unified format; the inquired video and the detected video are carried out the video structure analysis, shots in the videos are segmented and key frames are extracted; an index is established for the key frames of the detected video, the key frames of the inquired video are utilized for carrying out the preliminary search of a video copy in the index, the detected video containing the similar content with the key frames of the inquired video is obtained, and the detected video is taken as the option video for the next matching; the similarity between the key frames of the inquired video and the sequence of the key frames of the option video is calculated, the matching of the sequence of the key frames is carried out, the similarity between the videos are confirmed, and the video with the high similarity is taken as a copy video source of the inquired video. The video copy detection method and the system can reduce the search space for the video copy detection and effectively improve the detection efficiency.