Abstract: Cell lines of Bcap37 and Bcap37/MDR1 (the high P-glycoprotein (P-gp) expressing cell line) were used as model to investigate the different accumulations of (E)-2-(4-(diethylamino methyl) benzylidene)-5,6-dimethoxy-2,3-dihydroinden-one (BYZX) in the two kinds of cells. It was authenticated that whether BYZX was the substrate of P-gp. Meanwhile, the inhibitive effects of BYZX on the P-gp were investigated by determining the fluorescence intensity of rhodamine 123 in the model cells, with and without BYZX. A reversed-phase high-performance liquid chromatography (RP-HPLC) method was used to determine the accumulations of BYZX in the two cells. The results showed that the amount of BYZX accumulation in Bcap37/MDR1 cells were as many as those in Bcap37 cells (P>0.05), and the concentrations of BYZX accumulated in the Bcap37/MDR1 cells did not increase when co-incubated with P-gp inhibitor verapamil. Furthermore, different concentrations of BYZX also had no effects on the efflux of rhodamine 123 (P>0.05). These results indicated that there were no interactions between BYZX and P-gp. BYZX will not be pumped out of the cells, and it also not inhibited the P-gp. It was the useful advantage for its absorption.