Abstract: A novel method for the determination of the stability constant of baicalin was developed. In potentiometric titration, the pH glass electrode was used as the indicator electrode. The automatic titration device was used. Potassium hydroxide solution was used as titrant. The titration curve of baicalin was drawn out, and two stage conditional stability constants of baicalin were calculated by the piecewise fitting formation function method. Compared with the literature, there is higher accuracy in this method, and a new method is provided for the determination of the stability constant of flavonoids.