1. A device for determining a disappearing direction, the device comprising: a moving target detecting unit configured to detect, in a plurality of video images, a moving target area where a moving object is located; a feature point extracting unit configured to extract at least one feature point on the moving object in the detected moving target area; a moving trajectory obtaining unit configured to track a movement of the at least one feature point in a predetermined number of video image frames to obtain a movement trajectory of the at least one feature point; and a disappearing direction determining unit configured to determine, according to movement trajectories of one or more moving objects in the video images, the disappearing direction pointed by a major moving direction of the moving objects.