Abstract: In the spent fuel reprocessing process, extractants and extraction systems are subjected to intense radiation from various types of rays. Under such strong radiation fields, these extractants inevitably undergo physicochemical changes, such as chemical bond cleavage or rearrangement, leading to the formation of a series of radiolysis products. This results in the degradation of the extractants’ performance. Compared to β and γ rays, α particles have a higher linear energy transfer (LET), which may lead to more complex radiolysis behaviors of the extractants. Previous studies on the α-radiolysis of TBP (tributyl phosphate) have mostly focused on endogenous forms. Thereby, the exogenous α-radiolysis effects of TBP were investigated in this paper. For the first time, a gas chromatography-mass spectrometry (GC-MS) method was established to simultaneously quantify three TBP radiolysis products: H₃PO₄, MBP (monobutyl phosphate), and DBP (dibutyl phosphate). Prior to quantitative analysis, the radiolysis products of TBP were derivatized to replace active hydrogen atoms in their molecular structures with silyl groups. This derivatization step aimed to reduce the boiling points of the products, ensuring their complete vaporization in the gas chromatography (GC) vaporization chamber. Additionally, an α-irradiation platform constructed using a cyclotron was employed for the first time to investigate the α-radiolysis behavior of the TBP extraction system. The study focused on the effects of absorbed dose, dose rate, pre-equilibrium nitric acid concentration, diluent type, water molecules, and metal ions on the main radiolysis products of TBP (H₃PO₄, MBP, and DBP). The results show that within the absorbed dose range of 0-400 kGy, the yields of H₃PO₄, MBP, and DBP all increase with the increase of α-irradiation absorbed dose. Within the nitric acid concentration range of 0.01-5 mol/L, the yields of the three products also increase with rising nitric acid concentration, but the yields of H₃PO₄ and MBP tend to saturate at 1 mol/L nitric acid concentration. The presence of water molecules and Zr(Ⅳ) in the system inhibits the radiolysis of TBP, and HOK (hydrogenated kerosene) also exhibits a certain inhibitory effect on TBP degradation when the absorbed dose exceeds 100 kGy. However, within the dose rate range investigated in this study (0-30 kGy/min), no significant effect of dose rate variation on the main radiolysis products of TBP is observed. The findings not only contribute to a more comprehensive and accurate evaluation of the radiation stability of TBP and its extraction systems, but also hold significant implications for the molecular design of new extractants and the development of spent fuel reprocessing technologies.