Abstract: To detect the quality of pure milk rapidly, its spectral characteristics were analyzed combining 3-D fluorescent spectra with multi-peak fitting method, and its main compositions were obtained. The results show that its excitation spectrum ranges from 250nm to 310nm, and the peak wavelength is 290nm. The main emission spectrum ranges from 280nm to 500nm with the peak adjacent to 330nm.Meanwhile, the fluorescent spectrum has five spectral peaks(Ⅰ~Ⅴ), where peakⅠis generated by some proteins under the influence of lactose, peak Ⅱis generated by fat and vitamin E jointly, peak Ⅲ is generated by protein directly, peak Ⅳ is generated by some proteins under some unknown influence, and peak Ⅴ is generated jointly by microelements including vitamin A, vitamin B1, and B6. The study results provide some basic principles for studying milk composition with fluorescent spectroscopy.