Abstract: A redox-responsive hyaluronic acid-vitamin E polyethylene glycol succinate nanoparticle loaded with paclitaxel (HA-SS-TPGS@PTX) was designed to investigate its mechanism for overcoming multidrug resistance (MDR) in non-small cell lung cancer (NSCLC) in vitro. HA-SS-TPGS@PTX nanoparticles were prepared using an emulsion-ultrasonication method. Techniques such as flow cytometry and confocal laser scanning microscopy (CLSM) were employed to study their effects on apoptosis induction, mitochondrial function, and the regulation of P-glycoprotein (P-gp) expression in PTX-resistant lung cancer cells (A549/T). Results showed that HA-SS-TPGS@PTX nanoparticles significantly inhibited the proliferation of A549/T cells in vitro, with an IC₅₀ of 1.35 μg/mL. The nanoparticles entered the cells via CD44 receptor-mediated endocytosis. The high intracellular concentration of glutathione (GSH) triggered the release of PTX and TPGS, which subsequently induced a decrease in mitochondrial membrane potential, leading to apoptosis. Meanwhile, HA-SS-TPGS@PTX also inhibited P-gp expression and ATP consumption, thereby blocking drug efflux. The design of HA-SS-TPGS@PTX provides a new strategy for overcoming MDR in NSCLC.