The reaction-extraction-regeneration system for the liquid-phase oxidation of benzene to phenol in the benzene-water-oxygen system was investigated. Phenol was extracted in the extractor to reduce the concentration of phenol in the benzene phase. As vanadium catalyst was oxidized to inactive species after the oxidation reaction, the regenerator was installed in the system to reduce the oxidation state of vanadium catalyst from V4+ or VO2+ to the active V3+ under H2 flow. The effects of various operating parameters including concentration of VCl3 catalyst, O2 and H2 flow rates, benzene bubble size, pH, surface area of Pt regeneration catalyst, the metal species, and amount of ascorbic acid were investigated. Ascorbic acid was employed as a reducing agent for helping reduce the V4+ form to the active form and therefore improving the activity of vanadium catalyst. VCl3 catalyst concentration of 10mol/m3 with pH of 3-4 in the reactor and Pt surface area of 0.05m2 in the regenerator showed optimal conditions for the system.