Abstract: Based on the reduction of Fe(Ⅲ) to Fe(Ⅱ) by penicillamine due to its sulfhydryl group and on the color reaction between the Fe(Ⅱ) ion and 2,2′-bipyridine to give a reddish orange colored complex with its absorption maximum at the wavelength of 524 nm, a spectrophotometric method for indirect determination of penicillamine in penicillamine tablets was proposed. The optimized conditions found were as follows: ① amount of 0.2 mol·L-1 HOAc-NaOAc buffer solution of pH 4.5: 2.5 mL; ② amount of 0.2 g·L-1 FeCl3 solution: 2 mL;③ amount of 1 g·L-1 2,2′-dipyridine solution: 2.5 mL; ④ time of reaction: 5 min. Linear relationship between values of absorbance and mass concentration of penicillamine was obtained (indirectly) in the range less than 26 mg·L-1, with detection limit (3S/N) of 0.01 mg·L-1. The proposed method was used in the analysis of penicillamine tablets, giving results of penicillamine contents in consistency with the labelled value with RSD (n=5) of 2.4%.