Vietnam 1,200 years ago, is an international trade center, and many countries of China, India and South China Sea Merchant Shipping between northern Vietnam. Indian monks often go along with the merchants, via the North Vietnamese, and have a brief stopover in Vietnam, Chinese monks also. Therefore, Vietnam has become a transit station between China and Indian Buddhism.This article made an observation in the same period of Chinese Tang Dynasty and Annan, and studied the type and propagating content of monks in Annan and the Tang Dynasty through literature materials of historical data, monks' biography. Buddhist travelogues, poetry, and notes. In order to understand the process of monks spreading Buddhism and blending of Buddhist thought, as well as to sub-contracting the development of Vietnamese Zen. The paper is divided into three parts, ”The outline of the development of Buddhism in Annan”, ”The monks' activities of the Tang Dynasty and Annan through Maritime Silk Road” and ”The patterns of interaction in Annan & Tang Dynasty Buddhist”.The results show that it wrote an important page in history for exchange of Buddhism in the Tang Dynasty and Annan in the South China Sea. It contributed a connotation blend to the two locations of the Buddhist. The Tang Dynasty monks can learn Sanskrit, the Kunlun language, able to work together to translate scriptures, and went to India to seek Buddhist dharma with the assistance of the Annan monks. Annan's Zen Buddhism due to the impact of the Tang Dynasty, Mahayana Buddhism. And there is a minor trend in Zen, Vinaya School, and Tantrism in the Tang Dynasty Buddhist because Annan's Theravada meditation.