In order to identify the quality of medical materials in current market of traditional Chinese medicine (TCM), a grating spectrum imaging device based on sweeping-style spectrum imaging technology is designed. It can use electrically-controlled displacement platform to scan the sample and form an image in the one-dimensional spatial direction by taking the advantage of prismatic grating. Then, the TCM′s spectrum cube is obtained through image joining together. This device has a low cost and can realize nondestructive detection of TCM rapidly without particular laboratory environment. The detected parameters are as follows: the response range of system′s spectrum, spectral resolving rate, spatial resolving rate and the stability of the whole system. We take Panax quinquefolium as an example to detect and then combine its spectral images to form the spectrum cube. Its spectral characteristics and spatial distribution of its total saponins are obtained by describing the characteristic spectrum curve and spatial distribution imaging of fluorescence intensity.