Tumor multidrug resistance (MDR) is a fatal obstacle to cancer chemotherapy. The combination of P-glycoprotein (P-gp) inhibitor and chemotherapeutic drugs is one of the effective strategies to reverse tumor MDR. Herein, a folate-decorated PCL-ss-PEG-ss-PCL based redox-responsive polymersome (FA-TQR-Co-PS) was constructed, which was loaded with P-gp inhibitor tariquidar (TQR), anticancer drugs doxorubicin (DOX) and paclitaxel (PTX). The results suggested that the FA-TQR-Co-PS with an apparent bilayered lamellar structure displayed good monodispersity, high drug loading capacity, superior stability and redox-stimulated drug release peculiarity. In vitro cellular uptake study demonstrated that FA-TQR-Co-PS increased drug accumulation into MCF-7/ADR cells via the TQR-induced P-gp efflux inhibition, and further improved targeting to tumor cells due to folate receptor-mediated endocytosis. Furthermore, the DOX and PTX cytotoxicity and proapoptotic activity against MCF-7/ADR was enhanced dramatically along with the administration of TQR, and the cell cycle was profoundly blocked in G2/M phase. The folate-targeted redox-responsive polymersomes loaded with chemotherapeutic drugs and P-gp inhibitor demonstrated noticeable synergistic effect against human MDR MCF-7 cells and successfully reversed drug resistance, which displayed high potential in overcoming tumor MDR as a novel drug delivery system.