Cave 323 at Mogao Grottoes, Dunhuang, was excavated in the early Tang Dynasty with unique images and combinations. The Divine Connection paintings on the north and south walls and the Precepts paintings on the east wall are all new subject matters of the Tang Dynasty, and also the only examples at Dunhuang. Bodhisattvas on the lower section of the north and south walls are much taller than those found in the Sui and other Early Tang grottoes at Dunhuang. The image combination of this cave is unique and never seen in other places as well. Cave 323 has attracted the attention of many scholars due to its special subject matters and combinations. Nevertheless, to this day, there is yet a conclusion on issues such as the date of the grotto, its image structures, and its religious function. This thesis is divided into three chapters: Stylistic Analysis and Date, Iconographic and Iconologic Study, Historical Background. This thesis aims to clarify the date of the cave through detailed stylistic analysis of mural painting to complement the insufficiencies of stylistic analysis of past scholars. It also explores the religious significance and function of the grotto through discussing the meaning of the images and their relationship with each other. The author included all walls in the thesis for comprehensive thinking. In addition, this thesis is also dealing with the historical background of Cave 323 to understand some aspects of Dunhuang Grotto Art in the early Tang Dynasty. The author believes that Cave 323 was a grotto where monks received Bodhisattva Precepts in the early eighth century. It is the earliest cave associated with the Bodhisattva Precepts among Mogao Grottoes. In terms of the date of this cave, the painting styles, such as the forms and dresses of the figures, landscape background, and the relationship between the figures and the landscapes, etc., resemble to those in Cave 217 dated to the early eighth century, therefore, Cave 323 should be dated at the same time, that is, in the early stage of the flourishing period of Tang. In terms of its structure and function, Cave 323 is a cave for monks receiving the Bodhisattva Precepts. The Precepts paintings on the east wall are based on the Mahāparinirvāṇa Sūtra, emphasizing strict adherence to the Bodhisattva Precepts. The Divine Connection paintings on the north and south walls show how monks make sentient beings convert to Buddhism by all means, which correspond to the spirit of Mahayana Bodhisattva in the Holy Practice Chapter of the Mahāparinirvāṇa Sūtra. The Holy Practice Chapter describes that after monks swear the twelve vows, they have to enlighten all beings. In addition, based upon the Dunhuang manuscripts and the scriptures of Bodhisattva Precepts, bodhisattvas on the north and south walls are fellow friends in the Bodhisattva Precept ritual; the One Thousand Buddhas are buddhas of the ten directions serving as witness preceptors; the west wall painted the Future Buddha Maitreya, representing the hope th