Abstract: Selective conversion of methane into platform molecule methanol is one of the ideal ways to effectively utilize natural gas resources. Photocatalytic technology with low carbon emission can activate and transform methane at room temperature and atmospheric pressure, whereas the methane conversion performance of aqueous photocatalytic system is still low. Oxygen defects-rich WO_3-x was firstly synthesized through hydrothermal method and then triphase photocatalyst WO_3-x/CFs was constructed by loading WO_3-x on carbon fiber (CFs) with polytetrafluoroethylene concentrate (PTFE). Changing the addition amount of PTFE, the surface wettability of WO_3-x/CFs can be regulated. The morphology, structure and surface properties of triphase catalysts were systematically characterized by XRD, SEM, water contact angle, electron paramagnetic resonance (EPR) and low temperature nitrogen adsorption-desorption. The results of visible-light photocatalytic experiments show that WO_3-x/CFs triphase system can significantly improve the conversion performance of methane into methanol. Methane conversion amount of the optimal WO_3-x/CFs-0.3 catalyst is 2522.20 μmol·g⁻¹, which is 1.76 times and 2.48 times of WO_3-x/Indium tin oxide conducting glass (Glas) and powder WO_3-x diphase systems, respectively. Methanol yield of WO_3-x/CFs-0.3 triphase system is 1918.83 μmol·g⁻¹, which is 2.81 times and 4.69 times of WO_3-x/Glas and powder WO_3-x systems respectively, and meanwhile methanol selectivity of triphase WO_3-x/CFs system is up to 76.76%. The enhanced photocatalytic performance of WO_3-x/CFs is primarily due to the gas-liquid-solid triphase interface formed by the hydrophobic catalyst. The consumed methane can be directly transferred to the catalytic interface through gas transport channel in CFs, promoting the activation and conversion of methane molecules. Additionally, the triphase photocatalytic system shows excellent cyclic stability and the methanol yield of WO_3-x/CFs-0.3 can still reach 1506.98 μmol·g⁻¹ after 6 cycles.