Trichloroacetamide (TCAcAm) is among of the nitrogenous disinfection by-products (N-DBPs) with high cytotoxicity and genotoxicity, which is usually detected at low concentration (μg/L) in drinking water. In this study, advanced reduction process (ARP) based on vacuum ultraviolet (VUV) was employed to eliminate TCAcAm. Compared with VUV, VUV/sulfide, and VUV/ferrous iron processes, VUV/sulfite process demonstrated excellent performance for TCAcAm decomposition, the higher removal of TCAcAm could be achieved by VUV/sulfite process (85.6 %) than VUV direct photolysis (13.5 %) due to the production of a great number of reactive species. The degradation of TCAcAm followed the pseudo-first-order kinetics well in VUV/sulfite process, and the pseudo-first-order rate constant (kobs) increased with increasing sulfite concentration. Reactive species quenching experiments demonstrated that eaq−, SO3·− and H· were involved in the degradation of TCAcAm. The in situ generated eaq−, SO3·− and HO· via VUV/sulfite process were identified by electron paramagnetic resonance (EPR), and the eaq− was proved to be the dominated species (relative contribution: 83.5 %) for TCAcAm decomposition. The second-order rate constant of TCAcAm with eaq− was determined to be 2.41 × 1010 M−1 s−1 for the first time based on competitive kinetic method. The complete TCAcAm degradation could be achieved at pH > 8.3, while TCAcAm degradation efficiency decreased to 11.9 % at pH 5.8. TCAcAm decay could be divided into two stages: rapid growth (sulfite dosage: 0.25-1.0 mM) and slow growth (sulfite dosage: 1.0-4.0 mM). The yield of eaq− was controlled by sulfite dosage, and the predict yield of eaq− increased from 3.69 × 10−14 to 2.58 × 10−12 M with increasing the sulfite dosage from 0.25 to 4.0 mM by Kintecus 6.80, which resulted in an increase in TCAcAm removal. Meanwhile, the presence of dissolved oxygen (DO), chloride (Cl−), bicarbonate (HCO3−) and humic acid (HA) posed negative influence on TCAcAm decomposition to various degrees. Dichloroacetamide (DCAcAm), trichloroacetic acid (TCAA), dichloroacetic acid (DCAA) and Cl− were identified as intermediate products, indicated that reductive dechlorination and hydrolysis coexisted during the degradation of TCAcAm in VUV/sulfite process.