Dynamical Protein structure in vivo is generally different from that of "frozen" crystal structure.Exploring protein dynamical structure is not only imperative to elucidate its biological function,but is also important to understanding the fundamental problems such as protein folding.In this talk Ill present some of our recent progresses in elucidating the protein dynamical structural changes and their relevance to the biological functions by using temperature-jump time-resolved mid-IR transient absorbance difference spectroscopy,a powerful tool to trace the changes of secondary structures in thermal-induced folding/unfolding dynamics of proteins.