The device that applies time resolution technology into the realization of the one-order derivative spectroscopy is presented. The prism divides the light beam with wavelength [EQUATION] that comes out of the monochromator into two beams, which are vertically parallel and have the same wavelength. Using the modulator’s ability of time resolution complementarily, two different wavelength light beams are obtained, the difference of the two beams is realized, and the first-order derivative spectroscopy is obtained. The experiment indicates that the system is able to get the first-order derivative spectroscopy which is better than the original spectroscopy in terms of resolution.