The Second Language Acquisition Study is mainly written for undergraduates of Chinese as a foreign language. It can also be used as a reference for other Chinese teaching staff and researchers. It can also be used as an extra-curricular reference book for language and literature majors. The Second Language Acquisition Research system introduces the basic concepts, the nature of the subject, the origin and the development of the second language acquisition study, the comparative analysis and error analysis, the interlanguage study and the second language acquisition order. , Krashen's language monitoring model, second language learner language system variation research, second language acquisition research social culture model, language input and interaction research, universal grammar and second language acquisition, pluralistic development model, second Cognitive model of language acquisition, individual differences in L2 learners.