In　this　paper,　we　focus　on　the　number　of　solution　for　the　Perspective-Three-point　problem　(P3P)　in　some　geometrical　constraints　of　3　points,　which　is　a　common　problem　in　applied　mathematics　and　computer　vision.　We　use　Wu＇s　zero　decomposition　method　to　find　a　complete　triangular　decomposition　of　a　practical　configuration　for　the　P3P　problem.　By　the　Wu＇s　method,　we　also　obtain　some　sufficient　conditions　under　which　there　are　multi-solution　for　the　P3P　problem.　©　2008　Springer-Verlag　Berlin　Heidelberg.