With the development of economic level and the improvement of people living quality, sunscreen products have become an indispensable part of people's daily life. And the crystallization of sunscreen products as the main phenomenon of instability has attracted great attention. At present, the researches on the crystallization of sun-screening agent in emulsion mainly focus on how to develop new coating carrier technology or optimize the formulations to avoid the occurrence of crystallization, but the research on the crystallization mechanism of sun-screening agent in emulsion is scarce. From the perspective of crystallography, this paper mainly analyzes the crystallization process and inhibition mechanism of sun-screening agent in emulsion, forecasts the development and research trend of sunscreen products. Using the inhibition mechanism of crystallization to improve the stability and efficacy of sunscreen products has important scientific significance.