Abstract: To realize automatic discrimination of geometrical contradictions in planetary transmission, a transmission scheme graph model was established based on planarity algorithm theory and connection features of the planetary transmission scheme structure. Using Demoucron Malgrange Pertuiset (D.M.P) algorithm, the planarity of graph model was judged. The relevant functional program was compiled. The correctness and the efficiency of the criterion of geometrical contradictions were both enhanced. Finally, the topological transformation theory was applied to analyze the inherent relationship of two types of connection scheme.