Individual differences refer to the differences in learners' own characteristics or personal factors that affect second language learning, including factors such as age, language ability, cognitive style, learning motivation, and personality. Of course, there are other factors that affect second language acquisition. Judging from the current research results, we cannot explain which individual factors play an irreplaceable role in the success of second language acquisition. Therefore, this article attempts to review the current research on individual differences, aiming to reveal the importance of individual differences research for learners' second language acquisition, and at the same time provide useful clues for future research in this area.