AbstractWith the development of multimedia technology, the rapid increasing usage of large image database becomes possible. To carry out its management and retrieval, Content-Based Image Retrieval (CBIR) is an effective method. This paper shows the advantage of content-based image retrieval system, as well as key technologies. Compare to the shortcoming that only certain one feature is used in the traditional system, this paper introduces a method that combines color, texture and shape for image retrieval and shows its advantage. Then this paper focuses on the feature extraction and representation, several commonly used algorithms and image matching methods.