Despite the fact that chromatographic fingerprint analysis has been used increasingly for the identification of Chinese herbal medicines, there is no recognized procedure for the establishment of characteristic fingerprint chromatogram. In this paper, a chromatographic response function (CRF) was introduced to quantitatively compare chromatograms obtained under different experimental conditions. As a result, the optimum experimental conditions for the establishment of characteristic fingerprint chromatogram could be identified. Moreover, since the proposed function involved data that were directly available from the workstation after each chromatographic analysis, calculation could be automated. In this paper, the function was successfully applied to obtain characteristic fingerprint chromatogram for Chinese herb Langdu.