Machining damage occurs on the surface of carbon fiber reinforced polymer (CFRP) composites during processing.In the current simulation model of CFRP,the initial defects on the carbon fiber and the periodic random distribution of the reinforcement phase in the matrix are not considered in detail,which makes the characteristics of the cutting model significantly different from the actual processing conditions.In this paper,a novel three-phase model of carbon fiber/cyanate ester composites is proposed to simulate the machining damage of the composites.The periodic random distribution of the carbon fiber reinforced phase in the matrix was realized using a double perturbation algorithm.To achieve the stochastic distribution of the strength of a single carbon fiber,a novel method that combines the Weibull intensity distribution theory with the Monte Carlo method is presented.The mechanical properties of the cyanate matrix were characterized by fitting the stress-strain curves,and the cohesive zone model was employed to simulate the interface.Based on the model,the machining damage mechanism of the composites was revealed using finite element simulations and by conducting a theoretical analysis.Furthermore,the milling surfaces of the composites were observed using a scanning electron microscope,to verify the accuracy of the simulation results.In this study,the simulations and theoretical analysis of the carbon fiber/cyanate ester composite processing were carried out based on a novel three-phase model,which revealed the material failure and machining damage mechanism more accurately.