Abstract: In this paper, a derivative linear regression method of multiwave length data is proposed. The method, based on the difference of derivative specific extinction coefficient between two-component at multiwavelenvth, can be applied to simultaneous spectrophotometric determination of two-interfering-component systems with interference of excipients or other absorptions which belong to primary or quadratic curve absorption. As an example, the availability as well as the suitable condition for simultaneous determination of amidopyrine and caffeine in compound amidopyrine and caffeine tablets have been studied. The measured 1st derivative absorptivity(dA/dλ) at 14 wavelengths were over the range of 296.3～274.9 nm and the data were treated with the suggested method. The results obtained are satisfactory both in recovery and in precision. This method is simple, rapid and can be used for the analysis of compound medicinal preparations.