Abstract: The twentieth century is an important stage in the development of Chinese and Vietnamese literature and literary theory. From the traditional oriental approach to literary theory, Chinese and Vietnamese literature has successfully completed a modern transformation by accepting Western literary theory and constantly localized innovation. These achievements, both in China and Vietnam,laid a solid foundation for the Chinese and Vietnamese literature to enter the modern era. This paper focuses on the core issues of Chinese and Vietnamese literary theory in the twentieth century, including the modern transformation and the acceptance and development of Marxist literary theory in China and Vietnam, and points out the similarities and differences in the form and historical evolution of Chinese and Vietnamese literary theories through comparative study, so as to come to a new understanding of the relationship between Chinese and Vietnamese literary theory and the national characteristics of literary theory from these two countries.