Abstract: The optimal condition for extracting pigment from Bauhinia blakeana Dunn flower was studied through ultrasonic-assisted extraction technology in this paper. Results showed that the optimal processing parameters of ultrasonic-assisted extraction were as follows : solid-liquid ratio 1 ∶80 ( g/mL) , ultrasonic power 120W, hydrochloric acid concentration 0.3mol/L, extraction time 40min. The study on the stability of pigment showed that the pigment was stable under these conditions of acidity and low temperature, and the pigment had a good light fastness. The K+, Na+, Ca2+, glucose, fructose, citric acid, and sodium benzoate could contribute to the stability of the pigment while the Zn2 +, Cu2 +, Mg2 +, Al3 +, Fe3 +, H2O2, Na2SO3had negative effect on the pigment stability.