Ultra-precision diamond turning with a fast tool servo (FTS) is one of the leading methodologies for the fabrication of optical surfaces. The selecting and optimization of machining parameters is one of the main factors that could influence the machining accuracy. A simple and feasible method to select and optimize the FTS machining parameters is presented in this paper. The primary meaning of this idea is that the machining parameters should match the FTS dynamics, that is, to select the parameters for higher fabricating efficiency but within the dynamical performance limits of the FTS. From a systemic viewpoint, a virtual machining Simulink model is built in which the designed surface data is used as the system input and the FTS dynamics as the control block, the responded output then can be considered as the virtual machining data. Though the simulation, the quantitative results to the designed shapes and machining shapes are achieved which are helpful to optimize the machining parameters. The surface data generation method for designed shape is discussed and the dynamical identification model of FTS actuator is given. An virtual machining example is also given in the end. The quantitative results indicate that the proposed method is feasible and effective, which can provide effective reference for the future real fabrication.