Syntactic complexity (also called syntactic maturity，or linguistic complexity)，isimportant in the prediction of the quality of student writings. Wolfe-Quintero et al. (1998)pointed out that a syntactically complex writer uses a wide variety of both basic andsophisticated structures，while a syntactically simple writer uses only a narrow range ofbasic structures.
In the past half century, researchers adopted many different indices tostudy the syntactic complexity and attempted to find out the relationship among the scores,the grades, the ages and the writing quality. Syntactic complexity is defined as “the range of forms that surface in languageproduction and the degree of sophistication of such forms” (Ortega, 2003). It is animportant factor in the second language assessment construct as described in Bachmans(1990) conceptual model of language ability, and therefore is often used as an index oflanguage proficiency and development status of L2 learners. Various studies have proposedand investigated measures of syntactic complexity as well as examined its predictivenessfor language proficiency, in both L2 writing and speaking settings, which will be reviewedrespectively.Syntactic complexity is also called syntactic maturity, referring to the range oflanguage production form and the degree of the form complexity.
Therefore，the length ofthe production unit, the amount of the sentence embeddedness and the range of thestructure type are all the subjects of the syntactic complexity.
English writing is an important way of communication, which can enhance the ability oflanguage acquisition in the process of second language learning.
As one of the language skills,English writing is very difficult to master. After many years, students still find that their writingis unsatisfactory and have many problems. It is widely acknowledged that much attentionshould be paid to English writing. At present our college English writing teaching is time-consuming and low effectiveness, for teachers spend a lot of time and energy reading andcorrecting students’ compositions, but the efficiency is not high; at the same time, studentsspend a lot of time writing, and the results are not satisfactory.The following conspicuous problems tend to exist in the English writing.
First, when givena topic, students tend to think in Chinese and do a translation job.
Second, students spend toomuch time avoiding grammatical errors in the process of writing, which leads to the ignoranceof the organization of the compositions in a comprehensive view.
Third, enriching the contentduring the writing process is difficult for students, for they fail to support their viewpoints withappropriate examples and strong arguments.
English writing is the weakest part in Englishlearning especially for Chinese Vocational college students. According to Basic Teaching Requirements for Vocational College English Course,developing students’ comprehensive abilities to use English language is the teaching aim ofvocational college English. In terms of writing, students should have the ability to master thebasic writing skills and accomplishing writing tasks of different types, including narration,description, argumentation and practical writings like business email or announcement.
Besides,their writing should have a clear organization and proper coherence; at the same time, studentsshould be able to write or describe something with adequate content and proper form indifferent situations, such as business situation.