Abstract: Content Based Image Retrieval (CBIR) is an important component of Content Based Retrieval (CBR) system. Its function modules and the new approach of Dominant Color Block (DCB) for feature extraction and image matching is summarized. A 3-D clustering technology and statistics calculation based Dominant Color Extraction (DCE) and Dominant Color Matching (DCM) is also realized. On the basis of the detail study of CBIR technologies, a CBIR system named SPRING and supporting WWW distribution is designed and implemented, it shows a good performance.