Plane wave expansion method was employed to simulate the bandgap of 2－D photonic crystals with Kagome lattice. The optimum structural parameters of photonic crystals with the largest complete bandgap were obtained. Complete bandgaps were obtained when the germanium columns were in the shape of circular,hexagonal and square,respectively. It is showed that the complete bandgaps can be attained steadily as the filling fraction is changed in a wide range for circular and hexagonal columns,and their band structures are similar.