The English title of a Traditional Chinese medicine（TCM） research paper is an independent genre with distinctive stylistic features. Trivial as they seem to be， preposition in titles are actually difficult to command. There are some outdated structures and usage regarding prepositions in English titles of TCM research articles due to negative transfer of mother tongue. In this paper， English titles of TCM research articles in Chinese from reputable TCM journals in 2011 were selected according to the four principles of representativity， reputation， accessibility and usability. Then software antConc was used to generate the wordlist and cluster. Qualitative and quantitative methods were adopted to analyze the distribution and usage of frequently-used propositions in English titles of TCM research articles. Our findings show that seemingly small prepositions have flexible usage and serve the purpose of conveying information. Whether prepositions are appropriately used or not may hinder the communication， or even give rise to misunderstanding， which ultimately has an impact on the citation of TCM research articles and even on the spread of Traditional Chinese medicine worldwide.