A new method for moving object auto-extraction is presented in the field of moving object detection and tracking.The background model is initialized using filtered image frames,which have been stored,and the background is updated continuously by the result of object detection in the process of moving object detection.The moving region is obtained by the difference of current frame and the background.Then the adaptive threshold is used to get binary image and link the edge.The outlines of moving regions in binary image are extracted,and false outlines are eliminated resulted from noise and imprecise background by enacting area threshold value according to the size of moving object.Boolean calculation is done to the original image with the mask image including outlines of moving region and the result of extraction is obtained.The experiment results show that the method can well extract rigid body and nonrigid body can be extracted well by the presented method.