Contradiction plays an important role in Louis Kahn’s works in which rationality and irrationality are equally displayed. In the process of pursuing forms and light, Kahn insists on real appearance of construction and opposes decorations when he deals with architectural details. This paper expects to get a general and systematical idea of the nodes by analyzing and classifying Kahn’s works, we can summarize Kahn’s style of detail design in distinction, concealment and contraposition, which can be included in his design philosophy of classicism and structure rationalism. For the classicism bringing out the distinction, concealment and contraposition, and meanwhile distinction is the significant part of Kahn’s rationality in architectural structure. It is the mutual function of tectonic order and classic pursuit that makes up the expression of Kahn’s nodes order.