Abstract: In order to improve the quality of peanut kernels, the fluorescence properties and reflectance spectra of peanut kernels were measured and analyzed with the fluorescence microscope, fluorescence spectrophotometer and a system for measuring the optical properties. The characteristic wavelengths of reflectance spectra used to discriminate between low quality peanut kernels and normal peanut kernels were obtained. A computer controlled optical testing sorter with trifurcate optical fiber of collecting and conveying light was developed,with which the test of sorting peanut kernels was conducted.