With the rapid development of China’s economy, intelligent transportation system has gradually become an inevitable trend in the development of modern traffic management. AS an important part of intelligent traffic system, license plate recognition system plays an important role in the management and control of modern traffic. This paper uses digital image processing technology to study the license plate positioning technology of color automobile images. Through image preprocessing, license plate positioning, character segmentation and character recognition, the image is processed to realize the recognition of license plate under different environments.