Titanium alloy Ti6Al4V is a typical aerospace difficult-to-machine material. In the milling process, the wear of cemented carbide tools will reduce the stability of the machining process, thereby affecting the machining efficiency and the surface quality of the machined surface. The tool rake face wear will lead to the decrease of tool edge strength, and affect the flow direction and fracture of chip. The wear mechanism of rake face is analyzed and the prediction model of wear depth of crater groove is constructed. Firstly, the stress field model of the rake face is constructed by using the analytical method, and the stress distribution and wear location of the rake face of the milling tool during the sliding of the chip on rake face are obtained. Based on the contact relationship between tool and chip, the temperature field model of rake face is established. Then, based on the stress and temperature distribution on the rake face of the tool, a prediction model of the crater wear depth of the milling tool considering the abrasion wear, adhesion wear and diffusion wear is constructed, and the prediction curve of the crater wear is obtained. Combined with the distribution characteristics of the crater wear zone along the cutting edge direction of the milling tool, the wear volume prediction model of the milling tool rake face with time variation is established. Finally, the influence of cutting width on rake face wear is verified by experiments, and the predicted results are in good agreement with the experimental measurements. The results show that with the increase of cutting width, the wear depth and the wear volume of rake face also increase. The results of this study provide a theoretical basis for the design of milling tools and the reasonable selection of cutting parameters for titanium alloy milling.