1. A system for segmenting foreground and background in a video, comprising: a video shooting module for shooting the video; a data reading module for reading each frame of the video; a primary segmentation module for receiving each frame of the video from the data reading module, establishing a plurality of Gaussian models in a first color space for each pixel of each frame, performing a matching processing between each pixel of a current frame and the plurality of Gaussian models corresponding to the pixel, and primarily segmenting the pixels as foreground and background according to the result of the matching processing, wherein a part of the plurality of Gaussian models being selected as background model and the rest as foreground model; and a segmentation rejudging module for performing a rejudging processing in a second color space to the foreground and background that are processed by the primary segmentation module, so as to obtain a finally determined foreground and background.