Sister Xiao (pinyin: zǐ mèi xiāo), also known as Uli Ulu, Zhantoxi, Libu, Mimi, is a musical instrument of the Buyi and Miao people, popular in Guizhou Province, southwest Guizhou, south Guizhou, Anshun and other regions.

The sisters' flute pipes are made of bamboo and are tied side by side with two six-hole flute pipes with the same length, thickness and pitch. Most of them are made of locally produced water bamboo. The specifications are different. The length of the tube is 25 cm to 40 cm, the inner diameter of the upper end is 1.3 cm to 1.5 cm, and the pipe openings at the upper and lower ends are transparent.

The sister Xiao is soft and lyrical, with bright highs and soft lows. Often used for solo. It can also be played in ensemble or as an accompaniment to folk songs. The music is mostly suona music, such as "Welcome to the Pros", "Pick up the Guest", "Leaving the Mother" (when getting married) and so on.