This study, with the help of the International Corpus of English, contrastively explores uses of relative clauses by students in Hong Kong, Singapore and British English within the framework of world Englishes (Kachru, Asian Englishes: Beyond the Canon, Hong Kong University Press, 2005, Indian Journal of Applied Linguistics, 15: 85-95, 1989; Kachru & Nelson, World English in Asian Contexts, Hong Kong University Press, 2006). First, in the Hong Kong data, there is probably a tendency to use restrictive relative clauses led by WHICH in places where non-restrictive relative clauses led by WHICH are normally expected. Second, there is another tendency in the employment of non-restricted relative clauses led by THAT in Hong Kong university students' written work and it is interesting to note that this phenomenon seems to be more widespread in Hong Kong student writing than in Singapore student writing and no such cases were found out in the British subcorpus. Given that some distinctive patterns traditionally considered as developmental errors in the language learning process may also be seen as evidence of linguistic variations, second language teachers may need some tolerance towards this variation and compromise between “autonomy” and “grammaticality” in today's society of world Englishes (McKay, International English in Its Sociolinguistic contexts: Towards a Socially Sensitive EIL Pedagogy, Routledge, 2008). 本研究借助国际英语语料库,在“世界英语”(Kachru, Asian Englishes: Beyond the Canon, Hong Kong University Press, 2005, Indian Journal of Applied Linguistics, 15: 85-95, 1989; Kachru & Nelson, World English in Asian Contexts, Hong Kong University Press, 2006)的框架下探讨了香港英语、新加坡英语和英式英语中学生英语作文里的定语从句的使用情况。香港英语似乎往往会在一般情况下使用非限制性定语从句的地方使用以which引导的限制性定语从句。在香港学生英语作文中似乎还存在用that来引导非限制性定语从句的情况,这种情况比在新加坡英语中要多,在英式英语中不存在。这些特点被传统地认为是发展中的语言错误,但从“世界英语”的角度来看,有可能是语言变体的特点。在当今世界英语的社会里,二语老师也许应该对这种变异有所宽容,并在语言“自主性”以及“语法性”之间取得一定的妥协(McKay, International English in Its Sociolinguistic contexts: Towards a Socially Sensitive EIL Pedagogy, Routledge, 2008)。