To retrieve high-frequency four-word clusters in a self-made EST ( English for Science and Technology ) Paper Corpus ，corpus software—Wordsmith Tools ，is used． Clusters searched out from the EST Paper Corpus are investigated from both structural and functional perspectives． Structural classification shows that ，clusters containing noun phrases with of in them ，clus- ters containing prepositional phrases ，and clusters including passive verbs are most widely used in the corpus． Functional classifi- cation of clusters reveals that ，referential clusters are most frequently used． In addition ，more than 40% of the clusters are relat- ed to professional topics in the field of natural sciences． In EST paper writing ，acquaintance with formulaic patterns of clusters in papers written by English native authors can help Chinese scientific and technical personnel develop an appropriate English writ- ing style ，thus to facilitate international communication of technologies．