Benzotriazole (BTA), which is extensively served as household and engineering agent, is one of the emerging and persistent contaminants. Despite the spirit to remove BTA is willing, the traditional wastewater treatments are weak. Therefore, the degradation of BTA via electron beam was systematically explored in this study. It turned out that after 5.0 kGy irradiation, even 87.5 mg L-1 BTA could be completely removed, and the irradiation conformed perfectly to the pseudo first-order kinetics model. The effects of solution pH, inorganic anions (CO32-, HCO3-, NO3-, NO2-, SO42-, SO32-, Cl-), and gas atmosphere were all explored. And results indicated that oxidative hydroxyl radicals played critical role in BTA irradiation. Additionally, presence of H2O2 and K2S2O8 promoted significantly not only degradation extent but also mineralization efficiency of BTA due to they both augmented the generation of oxidative free radicals. Moreover, by combining theoretical calculations with experimental results, it could be inferred that degradation of BTA was mainly carried out by the benzene ring-opening. Further toxicity evaluation proved that as irradiation proceeded, the toxicity alleviated. Taken together, there were various indications that BTA could be effectively eliminated by electron beam irradiation in aquatic environments.