In this paper, a universal description of the optical coherence is represented, where the quasi-monochromatic optical field
and the corresponding coherence are expressed by Dirac state vector and the coherence operator, respectively. The
spatial coherence, the temporal coherence, and the partial polarization state are described by the abstract operator i. e.
coherence operator. With the operator method, the description of the optical coherence becomes simple and flexible, and
reveals the essence of the optical coherence.