The MahāmāyūrīVidyāRājñīSūtra is one of the dharani sutras of esoteric Buddhism known very well for praying for rain since the ancient time. It has undergone many ups and downs ever since its transmission from India to China 1,000 years ago. In the Tang dynasty, the sūtra was used by Amoghavajra to pray for rain with a great success, thereupon, it was listed one of the state’s sutra protecting of Tang. According to the ancient catalogs studies of Buddhist tripitaka, the MahāmāyūrīVidyāRājñīSūtra has been translated into Chinese up to nine times, but unfortunately, only six translator’s names are known and six translations are extant. The MahāmāyūrīVidyāRājñīSūtra consists of metta, triple gem, and name chanting three categories, functioning mainly as a sutra for safeguarding purpose. Among the contents, the not-to-be translated secret mantra belongs to the mantra by which the Buddha uses to teach his disciples. In the sutra, all Buddhas, bodhisattvas and dharma safeguarding deities are displayed orderly in the mandala to form a large dharma realm mandala. Through the establishment of the mandala, tanka, ritual procedures and altarpiece, practitioners are enabled to experience the attainment of three mysteries in one that there is no difference between the practitioner, sentient beings and the Buddha. In the glorious era of the Tang dynasty, other than being revered as the state’s sutra protecting the whole nation, the Mahāmāyūrī Vidyā Rājñī Teaching was also regarded a kind of practice taking up by Chan practitioners. In addition, not only MahāmāyūrīVidyāRājñī is the body of continuity of sameness of Mahāvairocana but also the transformation body of Amitābha as well. Hence, one can see that the MahāmāyūrīVidyāRājñī Teaching is being combined and integrated into the pure land and Chan’s teaching, which makes it a superior and distinctive teaching for ones to encounter. Therefore, in this thesis, a total of five chapters were devised to explore the foundational meaning of this sutra. First, the historical position of the MahāmāyūrīVidyāRājñīSūtra in the sutra catalogs recording was reviewed. Second, different versions of Chinese translation along with the equivalent texts in Theravada were compared and analyzed so as to uncover what may have been the protocol version of the MahāmāyūrīVidyāRājñīSūtra, its devolvement and unique characteristics etc. And then, the core message secret to this teaching was illustrated by using the descriptions in the mandala, tanka and ritual procedures. Finally, the stories of those famous monks who had practiced the MahāmāyūrīVidyāRājñī Teaching approach in the past were exemplified, so as to show the uniqueness of this cultivation method approach.