Abstract: Content-based image retrieval （CBIR） is an advanced project in the recent research area of multimedia retrieval. Indexing by color features is the important technology of image retrieval. In this paper, a new kind of image feature, dominant color moment （DCM）, which reflects spatial information of images, is taken into account on the basis of the image feature of dominant color （DC）. A method of similarity measurement is discussed based on the improvement of quadric form distance function. A kind of interactive model between man and system, called dominant color selection, is also proposed for precise retrieval according to different requirements imposed by different dominant colors in images submitted by users. Such a system shows good effect in the CBIR experimental system implemented by means of WWW distribution.