OBJECTIVE To establish the fingerprint of Huangqin decoction （HQD）， to separate the phase states and screen the active phase states of antidermatophytic activity so as to study the spectrum-effect relationship. METHODS HPLC method was adopted using baicalin as reference， the fingerprints of 10 batches of HQD were drawn and the similarity evaluation was carried out using the Similarity Evaluation System of Chromatographic Fingerprint of TCM （2012 edition） to determine the common peak； the phase states of HQD were separated and characterized by high-speed centrifugation and membrane dialysis. The minimum inhibitory concentrations （MIC） of HQD and its different phase states against Trichophyton mentagrophytes were determined simultaneously. Using the peak area of 37 common peaks as independent variable， MIC as dependent variable， Pearson correlation analysis was performed by using SPSS 21.0 software. RESULTS A total of 37 common peaks were obtained in HPLC fingerprints of 10 batches of HQD， with the similarity higher than 0.99. Ten components were identified， such as albiflorin， paeoniflorin， liquiritin apioside， baicalin， melaleuca glycoside A， wogonoside， baicalein， glycyrrhizic acid， wogonin and oroxylin A. HQD was split into 3 phase states， such as precipitation phase （HQD-P）， solution phase （HQD-S） and nano phase （HQD-N）. The morphology of HQD-P was irregular granular， and the average particle size was 4.670-91.522 μm. The morphology of HQD-S was uniform flakes， and no particle size was detected. HQD-N was spherical in shape and the particle size was （129.0±12.9） nm. MIC values of each phase state of HQD against T. mentagrophytes in different phase states were HQD-N （4.64 mg/mL） ＜HQD （5.85 mg/mL） ＜HQD-P （7.37 mg/mL） ＜HQD-S （12.89 mg/mL） at the same dosage. Pearson correlation analysis showed that the peak area of 25 of the 37 common peaks （including identified components） was significantly negatively correlated with MIC （absolute values of correlation coefficient＞0.95 and P＜0.05）. CONCLUSIONS The chemical composition of 10 batches of HQD is consistent； HQD-N is the active phase state of HQD. Ten components such as paeoniflorin， liquiritin apioside and baicalin may be the main active components of HQD. The antidermatophytic effect of HQD is closely related to its component content and physical phase state.