The maximum absorption wavelengths of rutin and quercetin are very close and their absorption spectra are seriously overlapping,so its very difficult to determine individually rutin or quercetin by spectrophotometry without prior separation.In this paper，a partial least squares-spectrophotometry was developed for the simultaneous determination of rutin and quercetin.The absorption spectra of rutin and quercetin mixed standard were studied in the range of 200-500 nm and the absorbance values were recorded every 2 nm.A partial least squares（PLS） model was built for the simultaneous determination of the contents of rutin and quercetin in the flos sophorae and synthetic samples.The results indicated that the recoveries of rutin and quercetin in the flos sophorae were in the range of 95.6%-99.8% and 99.8%-99.9%,respectively,and the recoveries of rutin and quercetin in the synthetic samples were in the range of 97.6%-102.1% and 100.2%-102.2%,respectively.The method showed high accuracy and satisfied precision,and could reduce the effect of noise effectively.