The invention relates to a method for launching advertisements in network video. A web page playing the network video comprises a video player layer. The method comprises the following steps: a server starts a buffer program of a video media when a network video playing instruction is triggered; the network video data are downloaded by the network, a plurality of hidden floating playing layers which are included by the network video web page are played, the server selects corresponding advertisements according to additional information of the network video while starting to download the video data, and an advertisement animation is loaded to a first hidden floating playing layer and the first hidden floating playing layer is displayed; meanwhile, the picture of the same advertisement is loaded to a second hidden floating playing layer, the first hidden floating playing layer plays the animation advertisement and then is hidden, the video player layer plays the video media, and the second hidden floating playing layer backprojects the advertisement picture behind the video player layer. The method causes more accurate orientation of the advertisement playing and the advertising effect to be more direct and more effective.