Mouth string is a simple musical instrument made of green bamboo. It has a unique timbre and is deeply loved by Qiang women. At present, there are only a handful of people in Beichuan Qiang Autonomous County who can skillfully make and play mouth string. The production process of mouth string is simple. It uses a piece of green bamboo about 10 cm long, with a small reed cut out in the middle, similar to the reed of a foot-operated organ, and a rope on one side. When playing, the right hand places the mouth string between the lips, and the left hand pulls the hemp rope, and the bamboo reed makes a sound. Its sound is elegant and lingering, but it is said that the range of the mouth string is narrow, not one octave, and can only play simple tones. The production of mouth string looks simple, but the reed is a very critical process. If you are not careful, you will not be able to achieve the effect of playing. The mouth string is very particular about playing, and the sound is transmitted through the vibration generated by pulling the hemp rope on one side. The change of melody depends entirely on the strength of pulling the hemp rope during playing, the position of the tongue touching the reed, the size of the mouth shape, and the strength of the airflow in the mouth. It is difficult to play. Mouth string is a musical instrument invented for Qiang women. When Qiang young men and women fall in love, the young men will make a mouth string and give it to the women to show their trust. This is the original Qiang mouth string. Later, Qiang women gradually mastered the skills of playing mouth string, and this instrument began to be passed down. However, as a unique musical instrument of the Qiang people, mouth string is facing the fate of being cut off from the past, and there are very few people who can play it. According to the information available, only Wang Zelan, He Xiufen and Zhou Shunlan from Shangwu Village, Qingpian Township can make and play mouth string fluently, and only Wang Zelan can play a complete song with mouth string. In ancient times, there were few entertainment activities and monotonous cultural life in the place where Qiang people lived. When they were tired of working in the fields and during the slack season, mouth string as a token of love became the best way for Qiang women to pass the time and relax. But I don't know when it started. When Qiang men and women fall in love, they no longer use mouth string as a token of love, but only as a leisure instrument. Nowadays, with the development of information and many ways of leisure and entertainment, few young people learn to make and play mouth string. Birth, aging, illness and death are the laws of nature that can never be changed. Nowadays, fewer and fewer of the older generation of Qiang people can play the mouth string, so the conscious inheritance of this ancient folk music by young people is extremely precious. The production of the mouth string is demanding and difficult. The golden bamboo used to make the mouth string has been cut down, and it is even more difficult to find golden bamboo. If other materials are used instead, the sound effect is poor. The Qiang mouth string and its descendants are in an endangered state and need to be rescued and protected.