英语写作中的句法复杂度是衡量作文质量的重要标准。现有研究主要针对学生写作中的不足，而很少从学生已经具备的能力出发，对学生的写作能力进行客观全面的评估。本研究通过自建语料库的方式，以高中学生的英语作文为研究对象，从英语作文中复杂句的使用频率、句型分类分析、正确率三个方面对复杂句的使用情况做了一个客观的描述分析,真实呈现当前高中学生英语写作中复杂句的使用情况，并对先前研究做出补充和完善。研究发现，当前中学生在英语写作中使用复杂句频率相对较高，且正确率超过80%，不足之处在于使用的句型较为单一，以宾语从句、状语从句和定语从句为主。概言之, 学生们作文中已经具备一定句法复杂度，但仍有很大提升空间。

In English writing, syntactic complexity is an essential criterion to evaluate students’ English ability. Previous studies have mainly studied mistakes and problems in students’ English writings. However, the overall evaluation of what students have acquired has been ignored. Thus, in this paper, in order to present the actual and objective situation of high school students’ complex sentences use, 166 pieces of English writings from high school students in Beijing were collected and then transcribed to form a mini-corpus for in-depth analysis from three aspects: frequency, main types, and accuracy. The results show that the frequency of complex sentences use is relatively high, and the accuracy is over 80%. Admittedly, the sentence types are relatively simple, for most of them are object clauses, adverbial clauses and attributive clauses. Generally speaking, current high school students have been equipped with the competency of using complex sentences in English writings to some extent, while there is still much room for improvement.