The sanxian is the only plucked string instrument without frets. As can be inferred from the name (san, lit. three; xian, lit. string), it has three strings. The sanxian family of instruments is very large, with different variants used in different tribes in China. The orchestra often uses dasanxian (da, lit. large) has a soundbox covered on both sides with python skin. Its sound is forceful, penetrating and articulated; in fact, a single sanxian can be clearly heard even in a 70-member orchestra.

It has a strong folk flavor, which often puts it in the limelight when in usage with other instruments. For this reason too, it is not suitable for playing accompaniment, as it tends to overshadow the sound of the melody instruments. It is more frequently used in plucked string ensembles and solos. Even when used in the orchestra, it is also attributed with the main melody. However, since the orchestral usage of the sanxian is lower as compared to the other instruments, sanxian players also take up a second instrument, which is usually the zhongruan.