The cutting process of carbon fiber reinforced plastic （CFRP） contains the fracture of fibers and cracking failure of resin matrix and interfacial phases.Meanwhile，the chip formation mechanism is diverse from different fiber cutting angle.Thus predicting the cutting force of CFRP effectively has been proven difficult.Combined with the principle of minimum potential energy and winkler elastic foundation beam theory， the deflection equation of fiber is obtained by calculating the microelement based on the representative element of CFRP （RVE） in this paper. The mechanical behavior of three cutting deformation areas with different fiber orientation angle is analyzed ，respectively.The prediction of critical damage length of the fiber is completed， which formed the analytical model of the cutting force of CFRP with different fiber orientation angle.The cutting force model is verified by the milling experiment of CFRP with straight edge milling cutter.When the whole fiber orientation ranges from 0° to 180°， the theoretical value of the cutting force and the experimental data is consistent with the variation trend of fiber orientation angle， and the relative error is within 15%.The cutting force increases first and then decreases with the increase of the fiber orientation angle. Both of them convert variation trend near 90° and 45°，respectively. The cutting morphology shows that when the fiber orientation angle turns 135°， the milling surface quality of CFRP is poor and the critical damage length is tremendous.The established analytical model of cutting force can predict the orthogonal cutting force of CFRP accurately，which can also provide theoretical guidance for the analysis of mechanical behavior in the forming of CFRP chips.