Abstract: Spectrophotometry was applied to the determination of trace amount of iron with Fe(Ⅲ)-chromazurine S-chlorpromazine hydrochloride ternary complex based on the fact that the chromogenic reaction of chromazurine S (CAS)and chlorpromazine hydrochloride (CPH) with Fe(Ⅲ). In pH 5.5 buffer solution of HOAc-NaOAc, Fe(Ⅲ)-CAS-CPH formed blue ternary complex of 1∶2∶2 with absorption maximum at the wavelength of 660nm and apparent molar absorption coefficient of 4.77×104L·mol-1·cm-1. Linear relationship between values of absorbance and mass concentration of Fe(Ⅲ) was obtained in the range of 0.02-1.2 mg·L-1, with detection limit (3s/k) of 7.6×10-3mg·L-1. Values of recovery found by standard addition method were in the range of 98.4%-99.5%, and values of RSD′s (n=5) in the range of 1.8%-2.3%.