The Buddhist thought of good and evil has rich levels and contents. Master Hui Si of Tiantai School expanded Mahayana thought of good and evil into three aspects: to break the persistence of good and evil’s substance, to set the phenomenon of good and evil’s dependent origination, to get rid of the opposition of good and evil and return to the non-duality middle way based on Mahayana teachings. This kind of thought is the origin of “nature having good and evil” theory, and its outstanding performance is to practice Mahayana wisdom and compassion in the form of evil.