In this paper, we develop an XML document retrieval system supporting a multimedia Web service for a digital museum. It can support unified retrieval on XML documents based on both document structure and image content. To achieve it, we perform the indexing of XML documents describing Korean porcelains used for a digital museum, based on not only their basic unit of element but also their image color and shape features. In addition, we provide a similarity measure for a unified retrieval to a composite query, based on both document structure and image content. Finally, we implement our XML document retrieval system designed for a digital museum Web service and analyze its performance in terms of retrieval time, insertion time, storage overhead, as well as recall and precision measure.