Ruan, the abbreviation of Ruan Xian, also means a long-necked pipa, similar in shape to today's Yueqin, which is different from the music-necked pipa passed down from Qiuci. Ruan Xian, one of the Seven Bamboo Sages of the Western Jin Dynasty, was good at playing the pipa. During the Kaiyuan period of the Tang Dynasty, a copper pipa was unearthed from Ruan Xian's tomb and named "Ruan Xian", or "Ruan" for short. The structure is a wooden round chime box with a straight handle, four strings and twelve columns, which can be played by hand when held vertically. In the Tang Dynasty, the pipa was used to convey orders in the army, so there is a saying that if you want to drink, the pipa will prompt you immediately.

In the Chinese orchestras developed in modern China, Ruan and Xian instruments include Zhong Ruan and Da Ruan. As the alto voice in plucked instruments.

After 1949, Ruan and Xian instruments were improved and developed into Ruan instruments, including treble Ruan, small Ruan, middle Ruan, large Ruan and bass Ruan. Among them, the treble ruan is used in the Hong Kong Chinese Orchestra to replace the Liuqin as a treble plucked instrument, while the middle ruan and the large ruan are commonly used in various folk orchestras as mid-bass plucked instruments.

The Ruan sound box is round, with twelve sound columns and four strings. It is played with false nails or picks. It can be used for solos, ensembles, singing and dancing accompaniments, or participation in ethnic band performances. It has rich artistic expression.