Protein is one of the most important living matters, and researches relatedto it have interested so many scientific workers. The secondary structure of protein plays a crucial role in maintaining protein's physiological activity. With the development of technology and the improvement of research technique, there are more and more in-depth studies on protein's microstructure. In recent years, many research works in this field have been done with different kinds of physical and chemical methods and Fourier transform infrared spectroscopy(FTIR)holds an unshaken position due to its unique superiority. The present paper is a general review of the related studies all over the world, and the assignments of the major infrared absorption bands of denaturized protein are introduced, and the spectroscopic features and the analytical methods are mainly reviewed.