Abstract: The gas-liquid mass transfer characteristics of three-phase system consisting of air,water/paraffin and sand/quartz sand/catalyst XNC98 was studied in a mechanically agitated reactor. At atmospheric pressure, the influences of operational factors and physical property parameters such as liquid property, particle size, particle density on volumetric liquid-phase mass transfer coefficient k_La were investigated under the conditions of superficial gas velocity range from 0.10×10^-2cm•s^-1 to 1.5×10^-2 cm•s^-1, solid concentration from 0 to 0.34 g•ml^-1（solvent）, impeller speed from 450 r•min^-1 to 1500 r•min^-1.k_La was determined by a dissolved oxygen electrode.A dimensionless correlation of k_La with the above factors was proposed and the parameters in the correlation equation were obtained with the improved Gauss-Newton method. The statistical test showed that the values predicted by the correlation equation were in good agreement with the experimental data.The results would provide basic experimental data for the subsequent process analysis and mathematical simulation of the three-phase methanol synthesis in agitated slurry reactor.