For　that　there　are　a　lot　of　independent　XML　documents　without　schema　need　to　be　processed,　the　authors　bring　about　a　mapping　algorithm　of　converting　from　XML　document　to　XML　document　tree,　and　then　to　relational　database　by　depth-first　search　and　makes　a　simple　comparison　with　other　algorithms.　This　algorithm　could　store　XML　data　into　database　and　restore　from　database　integrated.　The　authors　give　an　example　to　prove　the　feasibility　and　validity　of　the　algorithm.