Abstract: Buddhism has formed various new cultural patterns which different from the Indian Buddhism since it was introduced into
China. But it followsthe question of the legitimacy of Buddhism in China all the time.Actually，sinicization of Buddhism conforms to the original dogma of Buddhism，which is the establishment of Second Truth of Buddhism that Transcendent truths is the basis of Secular truths. Taking Tang Dynasty as an example，Chinese monks practice Buddhism with Confucian ethics leading to new features of Chinese Buddhism with Confucian ethics such as the unity of gentleman and the Buddha，patriotism and love of religionas well as loyalty and filial piety which accord with the establishing principles of Second Truth and answer the question of the legitimacy of Chinese Buddhism.

Key words: sinicization of Buddhism, establishment of the Second Truths of Buddhism, monks in Tang Dynasty, practice Buddhism
with Confucian ethics, legitimacy