Abstract: In HOAc-NaOAc buffer solution at pH 4.2, methyl violet could react with ferulic acid to form purple complexes with an obvious negative absorption peak. The maximum negative absorption wavelength was at 565 nm. Linear relationship between values of absorbance and mass concentration of ferulic acid was obtained in the range of 0.1-3.9 mg·L-1 , consistent with Beer′s law. The apparent molar absorptivity (ε) was 4.36×104L·mol-1·cm-1. The method was applied to the determination of sodium ferulic acid in commercially available sodium ferulic acid, giving values of recovery and RSD in the ranges of 99.5%-103% and 1.3%-1.5% respectively.