Abstract: N,N,N',N'-tetraoctyl diglycolamide (TODGA), as a high-performance amide extractant, shows great potential in the treatment of high-level radioactive waste (HLLW). However, under practical conditions, extraction systems are inevitably exposed to intense radiation environments, particularly continuous irradiation by α-particles with high linear energy transfer (LET). Such irradiation induces radiolysis of the extraction system, thereby affecting extraction efficiency and operational stability. Meanwhile, hydrogenated kerosene (HOK), as a commonly used diluent in TODGA-based systems, also directly influences the radiolysis behavior and extraction performance due to its radiation stability. Previous studies on α-radiolysis of TODGA are mostly based on long-lived radionuclides, such as ²³⁸Pu, ²⁴¹Am, and ²⁴⁴Cm. However, these radionuclides usually require long irradiation periods and present difficulties in post-irradiation separation from samples. Therefore, in this work, a short-lived radionuclide, ²¹¹At, was employed as an internal α-radiation source to systematically investigate the α-radiolysis effects in the TODGA/HOK system. The major liquid and gaseous radiolysis products generated in the TODGA/HOK system were quantitatively analyzed under different absorbed doses, pre-equilibrated nitric acid concentrations, and irradiation temperatures, and the corresponding extraction performance toward a representative lanthanide, Eu(Ⅲ), was also investigated. The results show that absorbed dose is the dominant factor affecting the radiolysis behavior and extraction performance of the TODGA/HOK system. As the absorbed dose increases from 10 kGy to 100 kGy, the degradation of TODGA increases significantly, with the degradation ratio rising from 21.8% to 32.4%. Among the liquid radiolysis products, N,N-dioctyl glycolamide is the predominant product, and its yield increases almost linearly from 0.91 mmol/L to 4.67 mmol/L. The main gaseous products are hydrogen, ethylene and methane, and their yields all increase significantly. In particular, the hydrogen yield increases from 2.6 mmol/L to 16.8 mmol/L. In contrast, the distribution ratio of Eu(Ⅲ) decreases markedly, with a reduction exceeding 50%. The pre-equilibrated nitric acid concentration shows an inhibitory effect on TODGA degradation, especially in the range of 3-5 mol/L, where the degradation ratio decreases by more than 30%. Meanwhile, increasing nitric acid concentration enhances the extraction ability of the TODGA/HOK system toward Eu(Ⅲ), and the distribution ratio reaches 92 under high acidity (5 mol/L). The effect of irradiation temperature on both the radiolysis behavior and extraction performance is relatively limited, and no significant overall variation is observed, indicating that thermal effects are not the dominant factor in TODGA radiolysis. The findings of this study not only contribute to a deeper understanding of the radiolysis behavior of TODGA-based extraction systems, but also provide valuable guidance for the further optimization of TODGA extraction processes.