Abstract: This paper studied UV spectra Character of natural green cotton pigment in ethanol solution by UV spectrophotometer. There is linear relationship between the absorption values and pigment concentration at 360nm, R2=0.9992. Then, compared with normal extraction,the efficiencies of ultrasonic-assisted extraction in various conditions were studied. Theresults found that the efficiency of ultrasonic-assisted extraction was significantly higher than normal extraction， ultrasound-assisted extraction of natural green cotton pigment 20min reached the same extraction efficiency to ordinary extraction 5 hours, and ultrasonic-assisted extraction and normal extraction obtain the same pigment composition.