Although composition and improvisation seem to be quite different, the creative level is the same . The narrow sense of composition is the result of the thought by written works as the carrier. Impromptu is improvised, is unable to carry out profound logical inference, with occasional more. Composing is in the logical space and improvisation is in the physical time. In the logical space composition, all creation material is to lay out, so the results are more controllable and quantifiable. But because of the time based on the physical time, it is a single and irreversible. The common and personality of the two is a breakthrough point in this article. This paper mainly discusses the creative work of the composer by comparing the similarities and differences between the composition and improvisation on the creative level