Abstract: The study on the width of English vocabulary has been one of the central issues in L2 (English) learning studies in China. Nevertheless, the vast majority of the previous studies have adopted the synchronic analysis, focusing on the width of English vocabulary among Chinese learners of English at a certain level. Few studies have been conducted as to the features of lexical width across levels. The authors of this paper, aiming at finding out the overall features of L2 (English) learners in the aspect of the width of their English vocabulary, have conducted two vocabulary tests among non-English undergraduates enrolling in 2001 and those in 2002 respectively. In the data analyses, the quantitative analysis has been adopted. Different perspectives have been taken to compare the features of students' mastery of English lexicon across levels. In addition, some pedagogical implications have been offered.