Abstract: In this study, in vitro cytotoxicity of carboxymethyl chitosan-rhein conjugate(CR conjugate)and paclitaxel-loaded carboxymethyl chitosan-rhein polymeric micelles(PTX/CR PMs)was evaluated by MTT method in MCF-7 cells. The results showed that CR conjugate displayed good security; PTX/CR PMs in 24 h showed better antitumor activity than Taxol^® . Environment-responsive fluorescent probe P4 was used to determine the cellular uptake of PTX/CR PMs in MCF-7 cells. The results also showed that P4 and PTX co-loaded carboxymethyl chitosan-rhein polymeric micelles ［(P4+PTX)/CR PMs］ could be taken up by MCF-7 cells. There was no difference between(P4+PTX)/CR PMs group and(P4+PTX)/CR PMs with verapamil group, suggesting that CR PMs could protect fluorescent probe and/or drugs in their cores avoiding efflux by P-glycoprotein. These results will contribute to in vivo study of CR conjugate and PTX/CR PMs in the future.