The objective of this study was to develop a polymeric delivery system to improve the solubility and biological activity of Quercetin (QT). QT loaded mixed micelles, composed of Pluronic P123 (P123) and D-a-tocopheryl polyethylene glycol succinate (TPGS) with proportion of 7:3 (QT-P/T), were prepared by thin-film hydration method. The average size of the mixed micelles was 18.43 nm, and the encapsulating efficiency for QT was 88.94 +/- 3.71%, drug-loading was 10.59 +/- 0.38%. The solubility of QT in QT-P/T was 5.56 mg/mL, which was about 2738-fold that of crude QT in water. Compared with the QT propylene glycol solution, the in vitro release of QT from QT-P/T presented the sustained-release property. The in vitro cytotoxicity assay showed that the IC50 values on MCF-7 cells for QT-P/T and QT loaded P123 micelles (QT-P123) were 7.13 microg/mL and 10.73 microg/mL, respectively, while 7.23 microg/mL and 14.47 microg/mL on MCF-7/ADR cells. From the results, it can be concluded that, P123/TPGS mixed micelles may serve as a pharmaceutical nano carrier with improved solubility and biological activity for QT.