<p>The cutting temperature distribution plays a key role in the surface integrity, tool life and sustainability during machining. Milling is a typical interrupted cutting process whereby the tool is continually subjected to cyclic loading, resulting in a notable fatigue damage phenomenon such as micro-crack propagation, especially for difficult-to-cut materials. Existing cutting temperature field modeling methods fail to account for the influence of thermal conductivity degradation resulting from fatigue damage on thermal behavior, which hinders the tool temperature prediction at different fatigue damage stages during milling. In this study, a milling temperature field prediction model that incorporates fatigue damage evolution by modifying heat conduction and partition behavior of the tool is proposed. Firstly, the loading and fatigue characteristics of the tool during milling are analyzed based on the kinematic analysis, and the fatigue crack propagation model is established. Furthermore, an equivalent thermal conductivity model considering the influence of fatigue cracks is introduced and the heat partition coefficient is modified accordingly. Subsequently, the tool temperature distribution is derived using the moving heat source method. The proposed method is verified by the milling experiments of Ti-6Al-4&#xa0;V, and the results indicate that the prediction errors of milling peak temperatures across different damage stages do not exceed 9.8%. The milling temperature variation can reach up to 32% under the influence of progressive tool fatigue throughout the milling process. The temperature field evolution under the fatigue effect primarily depends on cutting speed and secondly on feed rate. Finally, a fatigue failure boundary map of the tool is established from the practical point of view. The developed approach can provide effective guidance for controlling milling temperature and optimizing tool use.</p>