This paper exemplifies the concept of"various Buddhas" and the function of "Buddha’s various manifestations" based on the principle "One in all,all in one" by studying the themes in image creation at Dunhuang Mogao Grottoes and the Longmen Grottoes.Though large-sized sutra illustrations appeared in the Early Tang Dynasty at the Mogao Grottoes,most front walls contain images related to Sakyamuni,showing that the faith was focused on Dharma-kāya and Sakyamuni.Nevertheless,the Mogao Grottoes completely differ from the Longmen Grottoes in image themes and forms owing to the differing functions and roles of the two Grottoes.