Advertisement insertion method and device in video-on-demand system

The invention discloses an advertisement insertion method and device in a video-on-demand system, which is applicable to a hybrid fiber coax network. The method comprises the following steps: video programs and advertisements are implanted into a content management server to generate an index file; the video programs, the advertisements and the index file are sent to a video server; a release management server generates a user interface for the video programs and supplies the interface to a set top box for video-on-demand service; the set top box acquires the video-on-demand addresses of the video programs and sends a video-on-demand request to a session management server, and the session management server forwards the request to the video server and applies for IPQAM video site resources; and the video server pushes the video programs and the advertisements to IPQAM equipment according to a play list and the index file generated by an advertisement management server and sends the video programs and the adver