Abstract: In order to study the bubbling characteristic of single bubble cap in stagnant liquid, double-sensor conductivity probe has been used to determine the phase interfacial parameters such as local void fraction, interfacial area concentration and mean bubble size at the conditions with different gas volume flux and different height. Distribution laws of these interfacial parameters have been achieved: the local void fraction profile exhibits a "core peaking" configuration at about r/R=0.42, moreover, the void peaking (locations) move gradually toward the center of the column along the axial; at the same gas volume flux, the interfacial concentration resembles the local void fraction in the distribution law along the axial; the mean diameter of bubble trends to decrease along the axial.