To estimate the thermodynamic properties of a multi-component system using traditional geometric models, lack of a physical meaning generates many puzzles during choosing a concrete method. In this paper, we introduced a perspective in terms of the molar quantity of the components in the sub-binary of a ternary system affected by the third component and deduced a new model to unify all other traditional geometric models (e.g. Kohler, Muggianu, Toop-Kohler, etc.) into one model. The effects could be represented by so-called contribution coefficients, whose values only depend on the degree of identity between the thermodynamic properties of the third component and those of the selected components in the sub-binary, and which gives the physical meaning for the present model.