The concept of the “essence” has an important significance to the study of essentialism, and discussion on “essence” must he traced to the period of Western classical philosophy, the history of Western philosophy is not the beginning of a study of “essence” category, it is with the development of the ancient Greek philosopher to the source pursuit. After Plato’s efforts，finally proposed and established hy Aristotle. Plato and Aristotle on the “essence” of study of deep research laid the essentialism of the Western Millennium flourish, hy analyzing the theoretical core of Western classical philosophy everyone’ 8 "essence"，clearly shows the development of concept “essence” in this period.