In semiconductor physics course,PN junction,gold-semi contact and MIS structure are common contact situations. However,when students learn these contact types,they often find it difficult to make a homogeneous and unified comparative analysis of these different contact types,and cannot form a unified knowledge system,which causes confusion in understanding. In this paper,a unified judgment method of energy band bending applicable to various types of contact is proposed which provides a unified statement for the energy band bending for various types of contacts from the perspective that the establishment of built-in electric field affects the potential energy of carriers and thus produces energy band bending. The formation of the built-in electric field is explained from the microscopic point of view of the carriers flow in the energy band. This judgment method can help students sort out the knowledge of various physical contacts in semiconductors so as to achieve the effect of drawing inferences in the energy band analysis learning.