Intrinsically disordered proteins (IDPs) do not shape into a stable and well-structured three-dimensional fold, while they are biologically active. The discovery of IDPs is in contradiction to the traditional "structure-function" relationship. In this review, the experimental and computational methods for the identification of IDPs, and the corresponding databases were summarized. Then, we introduce the structural features (including primary structure, secondary structure, disorder of protein domain and the allosteric effect) and functional features of IDPs. We also specially focused on the evolutionary researches of IDPs. The evolutionary mechanisms of the formation of IDPs and the evolutionary rates of disordered regions were described. And the important roles of IDPs' evolution in the evolution of biological function and the increasing of biological complexity were summarized. Finally, we discussed the prospects of IDPs in medical applications. This review is of great significance for the further understanding of IDPs' formation mechanism, structural and functional characteristics and their potential prospects in clinical application.