Numerical simulation and experimental studies are conducted on the dynamic characteristics of powder flow rate and particle size distribution in a closed-circuit pulverization system. The performances of pulverizer and classifier are modeled by use of experimental data. The returning powder flow rate is taken into consideration, and material balance equations of each size range are numerically solved by an iterative method. It is confirmed by simulation that product and returning powder flow rate, and product mass median particle diameter increase with time and they finally reach constant values. The process stabilization time depends mainly on the converged value of returning powder flow rate under different operating conditions of pulverizer and classifier. Experimental data about dynamic characteristics agree with the simulational results, and the reliability of the present simulational method is confirmed.