Aim To investigate the transcytosis mechanism of chlorogenic acid(CGA)by using Caco-2 and MDCK(Madin Darby canine kidney) monolayers models.Method ① Caco-2 and MDCK cell models:Caco-2 cell(105 cells/cm2) and MDCK cell(5?104 cells/cm2) were inoculated in Millicell-CM culture plate inserts,and the TEER of cell monolayer were detected to make sure the models are available for experiments.② Permeating experiments: to measure the value of OD of CGA and calculate the cumulative amount.Result CGA could be Absorbed and secreted on two monolayer models.Verapamil could inhibit the secretion at lower concentration of CGA on MDCK monolayer model.P-pg could partly act on the secretion of CGA on Caco-2 and MDCK cell models.Conclusion CGA can secrete and Absorb at the same time across Caco-2 and MDCK cell monolayers,P-pg partly involving in the secretion of CGA.