OBJECTIVE:To establish a method for the content determination of total flavonoids in Morus alba. METHODS: UV-visible spectrophometry was performed with Al(NO2)3-NaNO2-NaOH color-test at the wavelength of 510 nm with the reference of rutin. RESULTS: The linear range of rutin was 0.031 2-0.156 mg/ml (r=0.999 9); RSDs of precision, stability and reproducibility tests were lower than 2%; recovery was 95.7%-101.0% (RSD=2.1%,n=6). CONCLUSIONS: The method is simple, stable and reproducible, and can be used for the content determination of total flavonoids in M. alba.