Abstract: The paper briefly introduces the history, principles, experimental setups, applications, and perspectives of two dimensional infrared spectroscopy (2D IR). The 2D IR technique obtains both static and dynamic molecular information through exciting molecular vibrations with ultrafast Mid-IR lasers. It is an IR analogue of two dimensional NMR, but six orders of magnitude faster. It has been widely applied to studies of molecular interactions, hydrogen bond dynamics, fast chemical exchanges, static and transient structures of peptides and proteins. More applications would be expected in the near future.