Zhang Zai's "Western Inscription" plays an important role in the philosophy of Song-Ming Neo-Confucianism. It is a refined piece of writing that contains broad and deep philosophical implications. This essay aims to present the content of "Western Inscription" and its essential meanings, including its metaphysics, ethics and theory of filial piety. It also compares "Western Inscription" with the Classic of Filial Piety. It is expected that through this essay the profundity and uniqueness of the philosophical meaning of "Western Inscription" are revealed.