Erhu is a kind of violin (fiddle) with two strings which, together with zhonghu, gaohu, sihu, etc, belongs to the "huqin" family. It is said that its origin would be dated up to the Tang dynasty (618-907) and related to the instrument, called xiqin originated from a Mongolian tribe Xi. During Song dynasty (960-1279), the second generation of the huqin was among the instruments played at the imperial banquets. During the Dynasties of Ming (1368-1644) and Qing (1644-1911), the erhu underwent a great development at the time of the golden age of the local operas. The erhu then developed in a different "schools". Two famous artists Hua Yanjun (1893-1950) and Liu Tianhua (1895-1932) made an exceptional contribution to the improvement of the erhu, and it was indeed due to the latter that the erhu, an instrument mainly for accompaniment in an opera, becomes a solo instrument. After the foundation of People's Republic of China (1949), the manufacture of the erhu, the playing techniques, the repertoire as well as the musical education of this instrument have undergone a rapid development. The repertoire has grown rapidly in the genres of solo, with ensemble as well as concerti with symphony orchestra.

The sound body of the erhu is a drum-like little case usually made of ebony or sandalwood and snake skins. It usually has a hexagonal shape with the length of approximately 13 cm. The front opening is covered with skin of python (snake) and that of the back is left open. The functions of this case of resonance are to amplify the vibrations of the strings. The neck of the erhu is about 81 cm long and is manufactured with the same materials as the drum. The top of the stem is bent for decoration. The two tuning handles (pegs) are found close to the end of the stem. There is no frets (as contrast to the lute) or touching board (as contrast to violin). The player creates different pitches by touching the strings at various positions along the neck of the instrument. The strings are usually made of silk or nylon. Nowadays, metal strings are commonly used. The bow is 76 cm long and is manufactured of reed which one curves during cooking, and arched with horse hair in the same way as the bow of violin. However, in the case of erhu, the horse hair runs between the two strings. In another word, one cannot take off the bow from the instrument unless one of the two strings is taken off or broken.

The posture which the player must adopt to play the erhu is the same as that adopted for the other kinds of huqin: the left hand holding the fiddle and the right hand, the bow. The erhu is put on the lap vertically, the left hand moves vertically to touch the strings for the right pitch while the left hand (with the bow) move horizontally to make the sound. occasionally some musicians hold the instrument with the help of a rope, in the same way as for saxophone, in order to play standing or walking. However it is quite awkward to play and it doesn't look elegant with the sound body pressing against the belly and the stem of the instrument pointing outward. Therefore, the musicians normally play sitted unless it's absolutely necessary.

The erhu sounds similar to human voice, and can imitate many natural sounds such as birds and horse. It is a very expressive instrument, most well-known for playing melancholic tune, but also capable of play merry melody.

The erhu often plays an important role in the national orchestras. In the smaller orchestras, there are usually 2 to 6 erhu, in largest, l0 with 12. In fact, the erhu plays the same role as the violin in the Western orchestras.