Characteristics of solid circulation rate in the liquid-solid circulating fluidized beds with viscous liquid medium were investigated. Effects of primary and secondary liquid velocities, particle size, liquid viscosity and height of solid particles piled up in the solid recycle device on the solid circulation rate were considered. The solid circulation rate increased with increasing primary and secondary liquid velocities, liquid viscosity and height of solid particles in the downcommer, but it decreased with increasing particle size. The particle rising velocity in the riser decreased with increasing the ratio of UL1/UL2 and particle size. The slip velocity of liquid and particle, UL/US, decreased with increasing liquid viscosity but it increased with increasing particle size. The values of solid circulation rate were well correlated in terms of operating variables and dimensionless groups.