语言习得理论的基础来自人类习得母语与自然环境潜移默化的作用、人类内在的生物本性及人类生物本性自身的发展规律。克拉申第二语言习得理论对近三十年语言习得各种研究成果理论化、系统化,成为当今世界影响最大的自成体系的语言学理论。克拉申的五个假设构成第二语言习得理论主要框架,对英语教学和英语学习具有重要的启发和积极的指导意义。克拉申的语言输入说简化了语言习得的过程,却很难通过教学实践验证其有效性,其理论仍需要进一步发展完善。 The theory of language acquisition derives from the subtle role of human learning in mother tongue and natural environment, the inherent biological nature of human being and the law of development of human biological nature itself. Krashen’s Second Language Acquisition Theory has made theoretical and systematic research on the various language acquisitions in the past three decades and has become the most self-contained linguistic theory in the world today. Krashen’s five hypotheses constitute the main framework of second language acquisition theory, and have important enlightenment and positive guiding significance for English teaching and English learning. Krashen’s speech input simplifies the process of language acquisition, but it is difficult to validate its effectiveness through teaching practice. The theory still needs to be further developed and perfected.