关键期假说从其问世以来就备受关注,虽然它最初是针对母语习得提出的,但却引发了无数有关二语学习年龄的研究和争论,争论的焦点在于:外语学习是否越早越好;究竟在哪个年龄段学习外语才能达到本族语水平。国内外的专家学者对此做了很多研究、实验,逐渐发现外语学习尤其是语音学习,并不是越早越好,很多晚学者在外语学习上也取得了成功。因此年龄到底在多大程度上影响着二语语音习得实际上仍然是个不解之谜。本文综述了国内外研究者对年龄因素以及与其有密切关系的因素——输入量的实验研究,并结合现在中国外语教学状况,试图探索中国环境下获得纯正的英语语音应该具备的条件。 Since its advent, the key period hypothesis has drawn much attention. Although it was originally proposed for mother-tongue acquisition, it has triggered countless studies and debates on the age of second language learning. The focus of the debate is whether foreign language learning is as early as possible ; At what age to learn a foreign language in order to achieve the native language level. Many experts and scholars at home and abroad have done a lot of research and experiments on this subject. They have gradually found that foreign language learning, especially pronunciation learning, is not as soon as possible and many late scholars have also achieved success in foreign language learning. Therefore, the extent to which age affects the second language acquisition is actually still a mystery. This article summarizes the researchers at home and abroad on the age and its close relationship with the factors - the experimental study of input, combined with the current situation of foreign language teaching in China, trying to explore the Chinese environment to obtain pure English speech should have the conditions.