The Bi of the Dai nationality consists of a tube body and a reed. The tube body is made of thin bamboo, with a bamboo joint at the upper end, a bamboo joint in the middle, and an open end at the lower end.

The size of the Bi of the Dai people varies greatly. Generally common, the tube length is 30 cm to 35 cm, the inner diameter of the lower opening is 0.8 cm to 1.2 cm, and the outer diameter is 1.5 cm to 2 cm. On the tube wall near the bamboo joint at the head end, there is a rectangular blowing hole, the hole is 1.5cm-2cm long and 0.4cm-0.6cm wide, and a reed is embedded in the blowing hole. The reeds are made of copper, with a sharp triangular tongue. The tube body usually has seven (six in the front and one in the back) circular sound holes. According to the number of sound holes, the minimum is four holes, and the maximum is eight holes. There is a treble button hole on the back of the tube body. The blow hole and the front press sound hole are in a straight line.