Ultra high molecular weight polyethylene (UHMWPE) has played in joint arthroplasty over the past years due to its outstanding wear resistance, mechanical properties and biocompatibility. However, oxidation caused by free radicals is one of the critical issues that jeopardizes the service life of UHMWPE joints. Therefore, it is important to eliminate free radicals so as to improve the oxidative resistance of the UHMWPE. As phenolic antioxidants, tea polyphenols could capture free radicals following the stabilization mechanism of hydrogen abstraction. In the present work, lipid-soluble tea polyphenols and its high-purity extractions were separately blended with medical grade UHMWPE and then irradiated at high doses. We found that the presence of tea polyphenols substantially prolonged oxidation induction time of the irradiated UHMWPE before and after accelerated aging. In particular, 0.2 wt% lsEGCG/UHMWPE blends presented nearly double and triple times of OIT value compared to the VE/UHMWPE counterparts at the radiation dose of 100 kGy and 150 kGy. The superior ability of tea polyphenols to quench free radicals was also proved by ESR. To further prove its applicability in clinic, we tested the oxidation stability of tea polyphenol-stabilized UHMWPE under the influence of simulated body fluid. The presence of squalene significantly shortened OIT of antioxidant/UHMWPE compared to the samples subjected to conventional thermal oxygen aging. Under such an aggressive oxidative condition, we demonstrated that lsEGCG significantly improved oxidation resistance of the irradiated UHMWPE compared to VE with proof of longer OIT and higher incipient oxidation temperature. These findings highlight lsEGCG is a promising candidate to give credits to the UHMWPE bearings with longer service span in clinic.