The absorption spectra and fluorescence spectra of lactobacillus plantarum are measured and studied by spectral analysis technique,and the results will be applied to the study and classification of probiotic bacteria. The results show that lactobacillus plantarum obvioushy absorbs ultraviolet rays and emits obvious fluorescence. The peak of aborbtion spectra is at 215 nm,and there is a shoulder peak at 280 nm which disturb the absorbtion spectra. The studies of the spectra show relevant information in cells about lactobacillus plantarum. The relations between fluorescence intensities and the concentrations are also studied and the change law of intensity with increasing concentration is found. The functions of data fitting based on the law are shown.