The Angsi Glacier or Nangser Glacier (Tibetan: ངང་སེར་འཁྱགས་རོམ, Wylie: ngang ser 'khyags rom, THL: ngang ser khyak rom) is a glacier located on the northern side of the Himalayas in the Purang County in China's Tibet Autonomous Region. It is immediately to the east of the Indus-Tsangpo water divide at the eastern edge of the Purang County. One of the headwaters of the Tsangpo River (Brahmaputra), called Angsi Chu or Nangser Chu, originates in this glacier. Angsi Chu merges with the Chema-yungdung Chu within a short distance (30°24′14″N 82°16′37″E / 30.4038°N 82.277°E), and the combined river is called Chema-yungdung Chu.
Swami Pranavananda, an Indian ascetic and pilgrim, noted in 1939 that the Tibetan traditions regard the Chema-yungdung glacier as the source of Brahmaputra. He also noted that Kubi Chu, another source stream of Brahmaputra favoured by Sven Hedin, is larger, and that the Angsi Chu gives greater length.