Syntactic complexity as an indicator in the study of English learners’ language proficiency has been frequently employed in language development assessment. Using the Syntactic Complexity Analyzer, developed by Lu (2010), this article collected data representing the syntactic complexity indexes from the writing of Chinese non-English major students and from the writing of proficient users of English on a similar task. The results indicate that there is a significant difference in the use of complex nominals, the mean length of sentences, and the mean length of clauses between the writings of EFL Chinese students and more proficient users. This study provides suggestions for EFL writing teaching, particularly writing at the sentence level.