In the past, High Tang period, namely the Emperor Xuan zung (玄宗713-755) era, was considered to have reached the peak of Tang culture spreading its influences towards the neighboring countries. In a closer examination, however, the brilliant creativity of Buddhist cave temple art in the late seventh and early eighth centuries had gradually lost its energy in the Xuan zung era. This paper analyses the center force of the transformation, especially the esoteric Buddhist art that reached China about this time. Furthermore, it further examines some Buddhist cave temples, which could be dated in the eighth century in order to explain how the transformation took place.