Sunü 素女, the "Immaculate Girl", is a figure in ancient Chinese mythology. She lived, according to the book Shanhaijing 山海經, in the region of Guangdu 廣都 (or Duguang 都廣, corresponding to Shuangliu 雙流 near Chengdu 成都, Sichuan) in the region of the "Black Waters" (Heishui 黑水), close to the tomb of Hou Ji 后稷, the Lord of Millet. The place was surrounded by a wall of 300 li (c. 150 km) of length, and was believed to be the centre of the world.
Sunü was an excellent singer. Her songs pacified wild animals and even supported the growth of vegetables and grasses.
The genealogy Shiben 世本 says that the mythological emperor Fu Xi 伏羲 had once created the zither (se 瑟 or qin 琴). The Yellow Emperor 黃帝 sent the Immaculate Girl to play the zither, yet she was not able to master the fifty-string instrument and therefore divided it into two parts, each with twenty-five strings. At least she was able to play this new instrument in an extraordinary way, as the book Guqin shu 古琴疏, quoted in the collection Shuofu 說郛, says. The universal history Shiji (chapter Fengshan shu 封禪書) renders the story somewhat differently and says that Sunü played the fifty-string zither in a sad way, and did not stop when the "Grand Emperor" (Tai Di 太帝) urged her to do so. He therefore smashed the zither, so that only a 25-string instrument was left. Sunü is also mentioned in the elegy Zhaoshi 昭世, part of the collection Jiuhuai 九懷 in the "Songs of the South", Chuci 楚辭.
The geographical treatise Shuzhong mingsheng ji 蜀中名勝記 explains that at Mt. Qingcheng 青城山 (close to Dujiangyan 都江堰, Sichuan), there was a Jade Girl Cave (Yünu Dong 玉女洞). The Jade Girl Yunü 玉女 was identified with the Immaculate Girl Sunü.
Sunü is also said to have been master of the art of the bedchamber (fangzhong shu 房中術). Hints to this matter can be found in the chronicle Wu-Yue chunqiu 吳越春秋 and the critical treatise Lunheng 論衡 (ch. Mingyi 命義). The bibliographical chapter Jingji zhi 經籍志 in the official dynastic history Suishu 隋書 lists three books dealing with the topic and related to the Immaculate Girl, namely Sunü yangsheng yaofang 素女養生要方 "The Immaculate Girl's important prescriptions for nourishing life", Sunü midao jing 素女秘道經 "Book of the Immaculate Girl's Secret Way", and Sunüfang 素女方 "Prescriptions of the Immaculate Girl". Such texts are also summarized under the title Sunüjing 素女經 "Book of the Immaculate Girl".