Abstract: In this paper, a new spectrophotometric method using programmable calculator has been developed for determination of three components systems. An improved algorithm for computing-analysis is proposed and programmed with the rotating coordinate method. Apreliminary theoretical exploration on this method is presented.By this method, the analytical results are obtained by application of TI-59 programmable calculator to analysize the spectrophotometric data measured, and the separation each other of constitutents needs to be not down.The method is a rapid and accurate one and convenient to spread. Not only provides it an adequate quality-controll procedure for pharmaceutical production, but also is significant for development of the analysis on polymixture components systems.