The invention relates to a method for extracting a foreground under a shaking background. The method comprises the following steps: S1) initializing the size of an image slide block, the step length of the slide block movement and the position of the slide block; S2) reading front and rear frames of images from a video and acquiring binary images be_frame and af_frame; S3) extracting the image slide block on the same position in the be_frame and af_frame, calculating a gravity center difference of two extracting results and acquiring motion vectors of front and rear frames on the current position of the image slide block; S4) moving the image slide block according to the step length and repeating the step S3) till completing the extraction for the whole image; S5) calculating an average motion vector of the front and rear frames according to all the acquired motion vectors of the front and rear frames; S6) reversely translating the rear frame image according to the acquired average motion vector, thereby acquiring a relieved shaking error image; S7) utilizing a Gaussian mixture model to extract the foreground for the front and rear frames of images after the shaking is adjusted. Compared with the prior art, the method provided by the invention has the advantages of wide application scope and the like.