The objective of this paper is to introduce the structural character of Exendin-4 and progress of research on treating type 2 diabetes mellitus by it after modification of its structure, so as to provide reference for further study. Retrieving literatures at home and abroad, according to the structural character of Exendin-4, inducing different method for modifying its structure and efficacy. The results were, Exendin-4 can promote secretion of insulin which depend on concentration of glucose, inhibiting increasing of postprandial glucagons, increase sensitivity of islet β cells and promote its proliferation, at the same time, also has the function of slowing gastric emptying and inhibiting appetite. Hence it is concluded that through the development of research on structure modification of Exendin-4, Exendin-4 will play a very important role in treating type 2 diabetes mellitus.