Continuous improvement of the component roundness accuracy through computer numerical control centreless grinding in high productivity is one of the most important issues particularly for modern automotive and bearings manufacturing. For instance, the process is towards 0.1–0.3 µm roundness accuracy in grinding the engine valve rod because of the increasingly stringent energy efficiency requirement in automotive engines. The characteristics of the computer numerical control centreless grinding process make it challenging, that is, how to assure the workpiece roundness generation in a predictable, producible, highly productive and scientific manner. In this article, a simulation-based industrial feasible approach is presented to model and control the workpiece roundness generation and its perfection strategies in computer numerical control centreless grinding. The kinematics of the workpiece in the process is presented according to the workpiece profile and its geometric configurations. Taking into account the workpiece geometric movements, contact and loss effect and grinding restrictions, a time-domain dynamic model is developed to provide the dynamics description of the workpiece, the grinding wheel and the control wheel in the process. The roundness generation of the workpiece is further predicted using this model. The effects of multiple factors on the workpiece rounding process are discussed and the influences on final roundness errors are investigated.