For upward cocurrent gas-liquid flow in a packed column, the gas-liquid flow pat- tern, liquid flow, and axial mixing characteristics were investigated. The transition boundary of gas-liquid flow pattern and residence time distribution(RTD) of liquid phase were measured in an air-water system. Based on experimental RTDs, parameters of mixing models were evaluated with three proposed mixing models : axial dispersion model(ADM), plug flow model with stagnant zone(PFM), and axial dispersion model with stagnant zone(DSM). Accordingly, the applicability and parameters of each mixing model were analyzed for various operating conditions. We found that the gas velocity at bubble-pulse flow transition boundary was increased with increasing liquid velocity and decreasing diameter of glass bead as a packing material, and that the flow and mixing characteristics of liquid phase could be well analyzed by DSM. Also, the fraction of stagnant zone estimated by the curve fitting method was decreased with increasing liquid velocity, while the mass transfer coefficient between dynamic and stagnant zones was increased with increasing gas and liquid velocities. In dynamic zone, the calculated Peclet numbers in both ADM and DSM were increased with increasing liquid velocity and decreasing diameter of glass bead. In these conditions, correlations of these parameters were obtained for various operating conditions.