Abstract: If the answer of an XML multi-keywords search is not empty,there would be some specific relationships between these keywords and such relationships can be speculated by SLCA (the smallest lowest common ancestor)．This paper proposed an XML keywords query results ranking approach based on these relationships:the approach obtains the SLCAs by the LISA II algorithm,leverages the structures of SLCAs to speculate the interior structural relationships of keywords and to obtain the relationship tree．Then,the importance of each SLCA can be estimated by the strict degree of keywords to the query node in the relationship tree.The SLCAs are ranked according to their importance and the ordered SLCAs are treated as the ranked XML keywords query results．The experimental results demonstrate that the approach presented in this paper has the high precision,and can efficiently meet the user’s needs as well．

Key words: Keywords search,SLCA,Twig query,Results ranking,Precision