I. Introduction

　　This research project is a case study of the learner language. I am interested in the inappropriate use of the auxiliary word 的‘de’ in Chinese L2 learners， for it is an obvious problem among non-native （English） Chinese learners. English is a language without the auxiliary word 的‘de’， whereas Chinese has obligatory using. My research is based on Obligatory Occasion Analysis （OOA） and target-like use analysis， which try to identify the usage of Chinese 的‘de’ and some wrong uses of this Chinese auxiliary word by the informant in terms. Then my research is analyzed with some relevant references from some literatures to explain the reason why the learner commits the errors. A test is given to collect the data.

II. Literature review

　　According to Gao （2005）， it is hard for foreigners to learn function words in Chinese，among which the auxiliary word 的‘de’ is the most problematic. As a function word， 的‘de’ is used to connect the attribute and the nouns and it is the symbol of attribute. But it is not always the case that all the attributes are followed by 的‘de’ （Liu， 1983）. And based on Gao’s research （2005）， omission of this kind of auxiliary word is a main common problems in L2 Chinese learning. English learners of Chinese always have tendency to omit 的 ‘de’ where a native speaker would use. From her research， Gao has pointed out that omission of the auxiliary word by English learners is systematic and that one of the principles， which can help to explain the omission of 的 ‘de’ by Chinese learners is because there is no such a word in English， and there are many exceptions to the rules guiding the use of the auxiliary word.
　　Tang and Zhu （2005） declare in their research that as a function word， omission is not the only main error the non-native Chinese speakers have when they use 的 ‘de’. Overuse is also a problem. The reason is that the Chinese language learners don’t fully control and understand the rules of using 的 ‘de’ and think too much about the usage， thus result in the phenomenon of overuse.

III. Methodology

　　1.Learner’s Background
　　For doing this research project， Matthew Chow， a 19-year-old male Australian， was chosen to be the informant for this research. He has learnt Chinese for about a year and is now studying it in the University of New South Wales. His mother tongue is English and Chinese level is elementary （Also see appendix1） 　　2.Task