Radial mixing characteristics of liquid phase have been investigated in the riser of a three-phase circulating fluidized bed(0.102m ID×3.5m in height). Compressed air and water have been used as a dispersed gas and a continuous liquid phase, respectively, while glass beads with the diameter of 2.1 mm have been used as a dispersed solid phase. Effects of gas(0.01-0.07) and liquid velocities(0.25-0.31 m/s) and solid circulation rate(2-8 kg/m²s) on the radial dispersion coefficient of liquid phase have been discussed. The radial dispersion coefficient of liquid phase was determined by using the infinite space model from the radial concentration profiles of tracer. As a result of this study, the radial dispersion coefficient of liquid phase has increased with increasing gas velocity and solid circulation rate, however, it has decreased with increasing not only liquid velocity but also bed porosity in the riser of a three-phase circulating fluidized bed. The radial dispersion coefficient has been well correlated in terms of operating variables such as gas and liquid velocities and solid circulation rate.