With the same topic as the writing prompt, this study aims at characterizing the vocabulary use by the English majors across four grades at tertiary level in China. The results indicate that the vocabulary type and family increase in accordance with the progress of language proficiency; the chunks identified from Grade 4’s writing seem fewer than those in the writings by the other three grades, and the most frequently occurring chunks may be affected and elicited by the topic prompt; among Grade1, 2, and 3, the learners tend to overuse or even formularize some ways of expressing views. Comparatively, Grade 4 learners display variety in their diction in that aspect; however, the accuracy and the appropriateness in semantic and pragmatic use would still be problematic to a certain extent, which somehow indicates a dearth of the width and depth knowledge of vocabulary in English learning.