The terms "orogeny" and "orogen" are both ancient classical concepts, which are widely used and have extensive influence. Following the rapid development of geosciences and the introduction of the plate tectonic theory during the past hundred and more years, the situation has greatly changed. How to refine these concepts so that they can be adaptive to modern understanding and meanwhile retain their original definitions has drawn wide attention. As a subject in the Conference on Review and Prospect of Structural Geology of China sponsored by the Committee on Tectonics, this paper presents a review of the historical background in which the concept of orogen was introduced; analyses the problems it is facing under the frame of plate tectonics, especially in modern continental tectonic researches; and proposes some common understandings concerning the re -understanding and applications of the concept in the new situation.