English writing becomes more and more important for college students. And we know that the composition consists of sentences and sentences consist of words. Besides, sentences can also be made of theme, rheme and transition.We should arrange them in the appropri_x005fate place of a passage, which makes the writing more perfect. Therefore, the application of the thematic structure in a writing plays an important role. We should realize its importance and know the use of it in order to make our English writing easier to read and understand.