In aerospace applications, avoiding chatter is an efficient way to improve the machining quality of weakly stiff parts. However, it is not easy to establish an accurate chatter stability model for variable curvature thin-walled workpieces under time-varying machining conditions due to their complex dynamic characteristics. For this issue, the paper proposed a chatter prediction model to effectively predict the chatter of variable curvature thin-walled workpieces considering material removal, cutter position, deformation along the cutter radius and axis, and other time-varying machining characteristics. Finite element simulation and milling tests to analyse the correctness in the proposed model. The proposed method contributed to chatter-free machining parameter planning to ensure machining stability.