The eunuch of Tang Dynasty harmed the political power, which was more serious than the Han and Ming dynasties. People believed this dated back to the reign towards Gao Li-Shi. This paper discusses Tang Hsuan-tsung‟s powerful eunuch, Gao Li-Shi, and Su-tsung’s powerful eunuch, Li Fu-Kuo, and analyzes their power types. The type of Gao Li-Shi called butler, which features that he arranged Tang Hsuan-tsung‟s private affairs and partook in government affairs. The type of Li Fu-Kuo called official. He managed the civil officials and government affairs, controlled the royal army, and passed on the orders of Su-tsung. His power was equal to the prime minister. The type of butler‟s power disappeared as he died. However, the type of the official‟s power could be inherited or transferred when he died or was dismissed. Thus, the source of the eunuch power in the middle-late Tang Dynasty began from Li Fu-Kuo.