The use of discourse markers is a common linguistic phenomenon in daily communication, which restrains the understanding of discourses. As an important cohesive device of discourse coherence, a discourse marker has many pragmatic functions such as restraint, prompt, discourse organization, etc. in communication, which helps readers/hearers make fewer efforts to achieve the most optimal contextual effect. With the development of linguistics, the study of discourse markers has become an important field, which has been developing quickly in recent years. The discourse marker So has abundant pragmatic functions, we should understand the different pragmatic functions based on different contexts.