Abstract: Physics simulation of carbon fiber reinforced polymer (CFRP) laminate machining is used to predict cutting forces, which is indispensable for the optimization of machining parameters and tool structures and the production of high-quality parts. The present cutting simulation models cannot accurately represent the CFRP laminate micro-structure, resulting in large deviations of cutting forces from the real values. This article proposes a new geometric modelling approach to the CFRP laminate micro-structure for physics simulations of its milling. First, based on the areal and volume densities of prepreg fiber and resin, the fiber volume fraction and the layer thickness are calculated. Second, a matrix of slender fiber cylinders is employed to represent the fibers, and the number and spatial spacing of the cylinders are determined according to the carbon fiber volume fraction and geometric constraints. Then, the parametric equations of the micro-cylinders in the 0°, 45°, 90°, and 135° fiber-angle plies are derived, and the geometric model of the CFRP laminate micro-structure is built. To demonstrate this approach, it is used to construct a CFRP laminate geometric model for cutting force calculation, and the calculated cutting forces are compared with the measured cutting forces to confirm its validity. This model increases the efficiency and accuracy of cutting force prediction.