The invention discloses a moving object extracting method and device. The method comprises the steps of: reading two frames of images from continuous a plurality of frames of images according to a predetermined frame interval, wherein the two frames of images are a first image and a second image; dividing the first image and the second image into a plurality of subareas, carrying out projection on the plurality of subareas so as to determine displacement vectors of the plurality of subareas, and determining a global displacement vector of the first image relative to the second image according to the displacement vectors of the plurality of subareas; determining ORB characteristic points of the first image and the second image, and obtaining matched point pairs of the two frames of images; eliminating background points of the first image and the second image according to the matched point pairs and the global displacement vector, and obtaining foreground points of the first image and the second image; and determining an initialization segmentation bounding box of a watershed algorithm according to the distribution of the foreground points, and extracting a moving object image according to the initialization segmentation bounding box. According to the invention, the problem that the segmentation of a moving object is incomplete under a dynamic background is solved, and characteristic points on the objects and characteristic points on the background are distinguished.