【Abstract】In recent years， language transfer has been attached great importance in the studies of second language acquisition and teaching. Both the positive and negative transfer should be paid great attention to. The influence of mother tongue is the core aspect in the transfer theory of second language acquisition. On the one hand， if the similarities of the two languages can be fully utilized and can produce results that facilitate the second language acquisition， the influences can be referred to as positive， and the transfer can be called positive transfer. On the other hand， negative transfer exists when mother tongue has inserted interferences which may cause errors in the second language acquisition process. Restrictions may occur in the acquisition process of second language.
　　【Key words】application； transfer theory； teaching abstract； Second Language Acquisition
　　Introduction
　　Language transfer， a significant aspect in language acquisition theory， plays an important role in second language teaching and learning and the studies of transfer have prevailed in researches of second language acquisition and teaching.
　　Diversified researches have been done on the phenomena of language transfer due to the different modes of thinking. In psychology， the term “transfer” is utilized to refer to the phenomena of automatic and unconscious use of the knowledge and behaviors acquired previously in the process of dealing with new things. Later， the studies of transfer have been applied on linguistics， which has made great contributions to the studies of language acquisition and teaching， within which， mother tongue is one of the core aspects and has been attached great importance in language acquisition.
　　The studies of transfer theory are of great significance and have been taken seriously by scholars， researchers and teachers. This is because language transfer is a universal and inevitable phenomenon， existing in all kinds of learning and training processes. By studying the functions of transfer， learning efficiency may be improved on the basis of effective teaching.
　　Transfer Theory
　　The concept of language transfer was first proposed by Robert Lado in his book Linguistics Across Cultures， who holds that mother tongue always serves as the basis of studying a second language. The transfer of language usually demonstrates in phonetics， form， grammar，， vocabulary and other aspects.
　　Generally speaking， language transfer refers to the influences inserted by the similarities and differences between mother tongue and the second language.