In this paper, we proposed a novel resolution criterion（improved calibrated normalized resolution product, r＊＇） to evaluate separation quality of fingerprints. By comparing with the calibrated normalized resolution product（r＊） and the hierarchical chromatographic response function（HCRF）, the validity of this criterion was demonstrated by experimental chromatograms. The soy isoflavone extract was selected as the analytical object. The initial and end percentages of methanol and elution time affecting gradient elution were tested by orthogonal design. The final optimized conditions were as follows. It was detected by UV absorbance at 254 nm, column temperature was maintained at 36 oC, solvent A was 0.1%（v/v） acetic acid, solvent B was methanol, gradient elution was from 34% to 65% B in a linear gradient in 25 min, and the flow-rate was set at 1.0 m L/min. In addition, the main ingredients of the soy isoflavone extract were confirmed by LC-ESI/MS.
