Steam plasma jet (SPJ) was generated by phenol aqueous solution introduced into water plasma torch as plasma forming gas, which injected into phenol aqueous solution to conduct oxidation degradation of organic pollutants in aqueous solutions. The experimental results indicated that the phenol was not only decomposed in SPJ, but also degraded in phenol aqueous solution due to high concentration hydroxyl radicals. Moreover, the energy efficiencies significantly increased from (1.6–1.8) × 10−10 to (4.8–8.0) × 10−8 mol · J−1 with the initial concentration of phenol increased from 0.5 to 50.0 g · L−1. The main intermediates of phenol decomposition were pyrocatechol, hydroquinone, maleic acid, butanedioic acid, and muconic acid in liquid. The major gaseous effluence products were H2, CO, and CO2.