Abstract: OBJECTIVE To study on transport characteristics of four marker constituents of Baitouweng decotion, namely aesculin, esculetin, anemoside B4 and berberine in Caco-2 cells by HPLC. METHODS Primarily, fingerprint and quantitative determination of four compounds was established. Subsequently, the double direction transport characteristics for those compounds were researched by Caco-2 cell monolayer model and verapamil, a selective P-gp inhibitor. Drug concentration determined through HPLC was applied to calculate the apparent partition coefficient (P_app). RESULTS The testing results for four compounds were shown below: ①The transport of aesulin from AP to BL was similar to BL to AP, which indicated its main mechanism in Caco-2 cells was passive transportation; ②The transport contents of esculetin from AP to BL was much more than that of BL to AP, and further experiments showed that the contents from AP to BL could be reduced by P-gp inhibitor verapamil. So, for those evidences, the mechanism of esculetin was active transference involved with P-gp; ③The transport of berberine from AP to BL was similar to BL to AP. However, P_app(BL→AP) was significantly lower than that of reference reported. One reason may be that the interaction between compounds or some one could restrained P-gp(BL→AP) activity to augment the absorption. ④It was a pity that anemoside B4 was unable to be detected due to its poor response to UV. CONCLUSION The transport characteristics of acsulin, esculetin and berberine can be detected by HPLC in Caco-2 cell model.