Abstract: We have compared the sensitization of various sensitizers to the coloration of chromium (Ⅲ) with chrome azurol S, and have considered to utilize the kinetic inert character of chromium complex in order to enhance the selectivity of the color development reactions.In this paper,a new sensitized multicomponent complex in the system of "Chromium (Ⅲ)——Chrome azurol S——Alkyl dimethyl amino acetai cacid"have been developed. The optimum condtions for the formation of the complex in this system have been studied.It was proved that the bromide of cetyl dimethyl amino acetic acid(CDMAA) or tetradecyl dimethyl amino acetic acid (TDMAA) is more suitable to be used as a sensitizer in the spectrophotometric determination of microamount of chromium with high sensitivity and selectivity. When CDMAA or TDMAA is used as sensitizer the molar absorptivity is 1.56×10⁵ or 1.88×10⁵ respectively.The sensitization of these two sensitizersare higher than all these sensitizers which had been reported formerly.