In　this　paper,　we　present　a　new　approach　for　defining　functional　dependencies　for　XML　(XFDs)　on　XML　Schema.　While　showing　how　to　extend　XML　Schema,　we　analyze　the　expressive　power　of　our　XFDs.　We　focus　on　supporting　complex　value　(e.g.　list,　set)　in　our　proposal.　A　novel　concept　match　tree　is　introduced　for　judging　the　value　equality　of　complex　type　elements.　The　satisfaction　of　XFDs　in　an　XML　document　is　defined　in　terms　of　the　value　equality.　We　also　discuss　the　advantages　of　our　XFDs　over　other　previous　work.