In this study, we established a simple and rapid in vitro method for screening multidrug resistance (MDR) reversal agents in traditional Chinese medicines (TCMs), which could better correspond to the MDR reversing effect in vivo. Here, D-luciferin, a substrate for the enzyme firefly luciferase and also a substrate for ATP-binding cassette transporters (ABC transporters), was used as the probe to detect its efflux kinetics caused by ABC transporters. First, we established a stable doxorubicin (DOX)-resistant cell line (MCF-7/DOXFluc) that overexpressed luciferase. Then, some kinds of TCMs were chosen for the MDR reversal agents to measure its effect on inhibiting the D-luciferin outflow from MCF-7/DOXFluc, and the ideal reversal agent with the least D-luciferin efflux from MCF-7/DOXFluc was selected to further investigate its effect combined with DOX on MCF-7/DOXFluc tumor-bearing mice. The results indicated that quercetin (Qu) could remarkably increase the retention of D-luciferin in MCF-7/DOXFluc in vitro and in vivo. Also, the combination of Qu and DOX could exceedingly inhibit the tumor growth, which proved the feasibility of this in vitro screening method. The study proposed a feasible method for mass screening of MDR agents from TCMs in vitro.