Abstract: Chatter in milling processes seriously affects machining efficiency and machining quality. Variable-pitch cutters improve milling stability through irregular distribution of tooth spacing angles, which disrupt the fixed time delay and periodic excitation that cause regenerative chatter, thereby weakening self-excited feedback and dispersing vibration energy. To enhance the chatter suppression performance of variable-pitch milling cutters, an optimization method for the tooth spacing angles of variable-pitch milling cutters is proposed, with the elimination of additional damping in the milling system as the optimization objective. A milling dynamic model for variable-pitch cutters is established, and the corresponding stability analysis algorithm is introduced. Numerical simulation and milling test results show that the optimized variable-pitch cutter exhibits higher milling stability. At 5 950 r/min, the stability limit cutting depth of the variable-pitch cutter is increased from 1.405 mm (for the equal-pitch cutter) to 2.425 mm, representing an improvement of 72.6%. Under the critical transition conditions where the equal-pitch cutter experiences chatter while the variable-pitch cutter maintains stable cutting, the root mean square (RMS) value of vibration of the variable-pitch cutter is reduced by 66.7%-78.4%. The above results verify the effectiveness of the proposed method.