With the development and progress of the economic and technology, transportation has become more and more important in human’s usual life. Intelligent transportation system can be used in many areas. Images in RGB color space are very sensitive to the environment light intensity, and what’s more, there may be some pollution appeared on the plate and so on, these made it difficult to locate the plate area. In this paper, we proposed some new algorithms. In the first stage, car image preprocess, a new algorithm named color division was proposed. Experiments show that, influences from the environment as well as some inevitably differences of colors in the plate into standard color, so the performance of whole system was improved. In the period of license location, a new algorithm based on license color pairs was proposed, and it has good performance after experiments.