A license plate location algorithm based on structure feature is proposed. Four features are used to extract the license plate region from the candidate regions. The thresholds of licence plate's structure features are given: (1) The license plate region's ratio of width to height is in the range of [2,5]; (2) The licence plate region's density is bigger than 0.25; (3) The licence plate region's gray-change time is in the range of [5,15]. A lot of experiments have shown that the algorithm has an accuracy up to 90.17%.