In recent years, the fiber optical communication system that uses optical soliton to transmit information has shown its advantages in long transmission distance and large capacity. It will play a great role in the new generation of communication and business. The transmission of optical soliton in optical fiber obeys the nonlinear Schr.dinger equation. In this paper, three commonly used methods for solving nonlinear Schr.dinger equation, i.e., Jacobi elliptic function expansion method, trigonometric function assumption, and trial function method, are analyzed and compared from the aspects of seeking traveling wave transformation, solving process and physical significance of solution, and so on. Moreover, we introduce the newly proposed (G′/G) expansion method. Calculation shows that (G′/G) expansion method is easier than the other three methods in traveling wave transformation and calculation process. Besides, it also has relatively rich solutions. Therefore, this expansion method solving the nonlinear Schr.dinger equation and the related equations has a wide application prospect.