Dynamics model on abrasive particles and workpieces during the centrifugal barrel surface finishing process was built by Discrete Element Method (DEM). The motion status of abrasive particles and workpieces was visually simulated and some important process parameters were numerically studied. The influence of planetary transmission ratio on finishing efficiency was analyzed, and finishing efficiency was the highest as the transmission ratio is -1. Finally, the conclusion was validated by experiments. Such economical and precise method could replace lots of finishing tests to optimize process parameters, which would provide theoretic basis for experimental research and efficient means for the finishing mechanism analysis of centrifugal barrel finishing.