Ruan is a stringed musical instrument in China. In the Qin dynasty, more than 2,000 years ago, people altered a wobbling drum into a stringed instrument. Later, with references to the zither and other musical instruments, people created "qin pipa". Qin indicted the Qin dynasty, and pipa was a kind of stringed musical instrument. Qin pipa was the predecessor of ruan.

Around 3 century AD, a musician named Ruan Xian was found to be extremely good at performing qin pipa. Due to his skillful performances, he was highly welcomed by the local people. Gradually the people named this musical instrument after Ruanxian. However, it was not called ruan until the Song dynasty, about 1,000 years ago.

Ruan is made up of three parts, the head, handle and the body. The head is usually decorated with some traditional Chinese imagery artwork such as the dragon. There are four tuning gages on the two sides. The body of ruan is an oblate resonance box. The structural theory, materials and performing skills are quite similar to those of pipa.

In recent years, Chinese people have paid more attention to the ethnic musical instruments. Some musicians have even made renovations to ruan, and developed alt, mediant, tenor and bourdon ruan.

The alt ruan, which is loud and clear, plays the role of performing the theme in the band. The tone of the mediant ruan is quiet and soft. It is used to perform the cantus and episodes in concert. It is abundant in variations of the rhythm while performing the accompaniment.

The big ruan is similar to the cello. While performed in the band, it often incorporates the median ruan, which may strengthen its sound effect. While performing the solo and chord, it may intensify the rhythm. The bourdon ruan sounds deep, similar to contrabass.