The canonization of Shakespeare’s plays is closely related to his inheritance and improvement of western literary tradition. Western literary tradition provides the raw material for the formation, development and reproduction of Shakespeare’s plays. Shakespeare borrows and adapts the plots from ancient Greek and Roman classics, uses the writing techniques of Italian writers skillfully, discusses continuously the themes greatly concerned by English writers and selects sources and historical materials from the Bible and the chronicles. In the course of inheritance of western literary tradition, Shakespeare imitates and recreates western literary tradition. He achieves great success in the using of poetic language, the portrayal of disguised characters, the reconstruction of dramatic structure, the development of critical ethics education, the publicization of enlightenment spirit, the portrayal of stereoscopical characters and interpretation of free-will destiny. Shakespeare makes great contribution to the development of western literature, even world literature, which makes his works be imitated and finally canonized.