The True-Mind of Complete Enlightenment is the principle interpreted by Zongmi (780-841) to explain that the completion of enlightenment applies to all phenomena. Based on the conformity of Buddhist teaching concepts and meditating realizations, the essence and the form are consistent; the mediation and the teaching have no difference; the reality and the delusion are one. Therefore, there is no conflict between the teaching and the realization. Stillness is interwoven with the conditional trend. Existing and non-existing are nondual in accordance with each other. Being and nonentity are in harmony with no obstacles. It gives the prominence to the realization of the Complete Enlightenment. Based on Two Aspects from One Mind in Awakening of Faith in the Mahayana, Zongmi dialectically initiates the structure of the Final Teaching to interpret the True-Mind of Complete Enlightenment applying to all phenomena [sarvadharma]. He connects the dependent arising of originate Suchness with the Interdependent Co-arising of Dharmadhatu in Huayen doctrines. The Dependent Arising of Suchness, which dominates all things, either pure or impure, interfuses consummately with One Mind of True Dharmadhatu. They absorb each other harmoniously, co-manage each other smoothly and expand themselves unlimitedly. One Mind is the mind of sentient beings. It means the ultimate one Mind of Dharmadhatu as well. The Mind is the essence of Dharmadhatu, the ultimate truth that contains all phenomena but also transcends all of them. The integration of Two Aspects from One Mind displays the ordinality, the difference and the relativity between the aspect of Suchness and the aspect of Birth-and-Death. It is also extended to cover all teaching doctrines. The essence of One Mind transcends all phenomena, either pure or impure to become absolutely superior harmony as a whole. The Substantial Mind [Hṛdaya] focused by Zongmi is the inherent true Buddha-Nature [Tathāgatagarbha] purely being free from birth-and-death. It is used by Zongmi to exemplify the core matter of One Mind and to support his philosophy that emphasizes the whole complete quality of One Mind. This Mind concatenates the Complete-and-Sudden teaching concepts in both Huayen and Tiantai schools to be one substantive center that coordinates the Interdependent Co-arising of Dharmadhatu in Huayen and the True Appearance of Middle Way in Tiantai. Hence, this dissertation contains four perspectives to develop the ultimate meaning of the True-Mind of Complete Enlightenment in Zongmi's Commentary on the Awakening of Faith in the Mahayana. It explains the interdependent co-arising of Dharmadhatu by Five Teaching Divisions and highlights True-Mind of Complete Enlightenment to integrate all teachings and meditating realizations. The combination even more extendedly covers the Complete Teaching and the Sudden Teaching in both Huayen and Tiantai schools. The thesis makes a thorough inquiry on the True-Mind of Complete Enlightenment at first. The manifestation of all phenomena is the realization of True-Mind. The teachings of all schools are integrated by endless unobstructed arising in Dharmadhatu. The intention is to coordinate the teachings and the meditating realization as a whole by cooperating Five Teaching Divisions. Secondly, the True-Mind of Complete Enlightenment in the Interdependent Co-arising of Dharmadhatu is discoursed. According to Zongmi in Commentary on the Awakening of Faith in the Mahayana, the unobstructed-ness, one of Four Dharma Explanations, consolidates other three explanations, which are phenomena, con-sciousness only and Suchness, to support the endless unobstructed arising in Dharmadhatu One Mind of Dharmadhatu interweaves with threefold contemplation of Dharmadhatu and four dharma dhatus, as well as manifests the inconceivable subtle truth. The third is to unfold the True-Mind of Complete Enlightenment by the classification of Five Teaching Divisions. Based on True-Mind of Complete Enlightenment, the connection of the Dependent Arising of Originate Suchness in Awakening of Faith in the Mahayana and the Interdependent Co-arising of Dharmadhatu in Huayen performs consummately. They absorb each other harmoniously, co-manage each other smoothly and expand unlimitedly. It reveals the perfect unobstructed-ness of One Mind and Five Teaching Divisions. The fourth is to reflect True-Mind of Complete Enlightenment on the identical teachings of Huayen and Tiantai. It unfolds the significant resemblance of Huayen Ekayana special teaching and Tiantai Ekayana common teaching indicated by Zongmi. The conceptions of the complete teaching and the sudden teaching in both Huayen and Tiantai schools are not different in the ultimate truth.