Abstract: It was found that when sibutramine hydrochloride (abbreviated as SBTM) was reacted with the mixed solution of citric acid and acetic anhydride at 80 ℃ in water bath,a purple black solution was obtained.The absorption maxima of the solution was found at 330 nm,and Beer′s law was obeyed in the range from 0.17 mg·L-1 to 18.5 mg·L-1 (r=0.998 9),with its detection limit of 61.5 μg·L-1.Molar absorptivity of the colored solution was found to be 8.16×104L·mol-1·cm-1.The proposed method has been applied to the analysis of 3 samples of SBTM capsules,the results obtained were in consistency with the results obtained by HPLC,and values of RSD′s (n=6) obtained were less than 0.5%.