Abstract: This paper provides a basic principle and experirrtental technique of derivativesignal multiplier spectrophotometry in multicomponent mixture. A microcomputer was used to processthe spectral data measured on a manual spectrophotometer (UV-7520) for the determination of morox-ydine hydrechloride in Gan Map Qing capsules. Quantitative analysis of multicomponent mixture canbe done without sample separation. The selection of optimal wavelength pairs is performed through theprogram with a computer. The method needs no special spectrophotometer, and is simple, rapid andeasy to operate. The mean recovery was 99.98±0. 53% (n=12).