To　mine　XML　stream　in　an　online　way,　a　data　structure　named　exponential　histogram　of　cluster　feature　for　XML　is　proposed.　The　structure　is　based　on　the　temporal　cluster　feature　and　can　be　maintained　according　to　the　exponential　histogram　rule.　The　experiment　results　for　a　real　data　set　and　a　synthetic　data　set　show　that　the　structure　is　of　higher　quality　than　the　method　offline.