Abstract: Cooperative authoring is one branch of CSCW. In the present paper, a technique of document catalog tree is proposed in cooperative authoring of WWW document, a hierarchical directory structure is extended for common WWW document to express its global structure, and a perfect infrastructure is provided for cooperative authoring. Also discussed are the details of the cooperation technique in team authoring based on document catalog tree, including the design of multi\|user interface, cooperation mechanism, and the concurrent control method of catalog path locking.