Abstract: In the synthesis of polymers and polymer composites, it is still a challenge to observe the real-time and dynamic evolution of material structure and provide implications for property prediction. As one of the methods to characterize the microscopic and submicroscopic structures of substances, small angle X-ray Scattering (SAXS) technology can reflect unique microscopic conformational information, and can systematically study the morphological characteristics and formation process of chain-like, network-like, and layered polymers. The analysis of the formation mechanism of the aggregated structure of molecular materials, and their macroscopic performance prediction are very important. In this paper, three common methods for SAXS applications in current polymer materials research were presented, i.e., the peak observation, the model fitting, and the annular integration. Based on the above three methods, this paper introduced the practical functions of SAXS in studying different polymer materials, such as dynamic observation of the microstructural evolution process, and obtaining large-scale and statistically significant microstructural parameters. After comparing and evaluating the application methods and influences of SAXS in different polymer materials, it was concluded that SAXS plays a comprehensive role that is difficult to replicate in the study of complex polymer materials. It was hoped that this paper could serve as a primer to attract researchers' attention to understand SAXS technology, provide alternative research methods for the investigation of complex polymers, and expand the application of SAXS in wider fields to solve more problems.