The invention discloses a character combination-based license plate positioning and identifying method used in a traffic video monitoring environment. The method comprises the following steps: carrying out pretreatment and binaryzation on an image; marking connected components so as to form an alternative character set; analyzing the spatial relationship between the connected components according to the ordering mode of the characters in a license plate; and deducing the specific position of the license plate, and obtaining each character area at the same time; and identifying the characters. The method has the advantages of high precision, strong robustness, less constraint condition and the like, and particularly, the partitioning of the character areas is accurately accomplished while the license plate is positioned. As the unique ordering mode feature of the characters of the license plate is utilized, the method has good adaptability to external complex environment, and a license plate target does not occupy any conspicuous position in a larger ratio in the image, therefore, the method is quite applicable to an urban road traffic video monitoring system.