The invention discloses a method for rapidly positioning a license plate in a video image. By the method, license plate candidate regions are rapidly segmented by utilizing a gradient shadow detection method and a one-dimensional filtering technology on the basis of vehicle bottom shadow characteristics and then are positioned precisely. The method comprises the following steps of: (1) extracting a frame of image in video and segmenting processing regions; (2) graying the images of the processing regions and performing gray stretch; (3) performing primary coarse positioning according to the vehicle bottom shadow characteristics; (4) de-noising by a one-dimensional filtering method and determining candidate regions; and (5) precisely positioning the candidate regions by using morphology. The method has the advantages of easiness in implementation, high robustness, high precision, high real-time performance and the like, and can provide a new real-time and reliable rapid positioning method for the license plate positioning in license plate identification.