"Grit" is often considered as an important positive psychological factor for success, and has caught the attention of scholars in the field of Second Language Acquisition (SLA) recently. A thorough study of grit’s influence on language learning will enrich its factor analysis on successful second language learning, and help to intervene and adjust the second language teaching methods. Therefore, this paper reviews the relevant literature on the L2-Grit, with a view to summarize the connotations of grit and its different relevant theories, exploring the positive effect of grit in promoting second language learning, and interpreting other factors affecting L2-Grit. Finally, considering the limitations of the present researches, the paper also puts forward suggestions for the future and prospects the development of L2-Grit.