Abstract: Against the dilemma of balancing production line flexibility and efficiency under the multi-variety and small-batch production mode in aerospace manufacturing, this paper proposes an optimization method for machining production lines based on value stream analysis, integrating lean production and digital technologies. Firstly, field investigation and data collection are conducted to draw the current-state value stream map. Production bottlenecks including unreasonable process flows, inefficient layout and logistics, long changeover time and backward production management modes are identified. Secondly, multiple lean production tools combined with on-machine measurement, zero-point quick-change and digital management systems are adopted to optimize processes, layout and logistics, realize rapid changeover and reform traditional production management, thus improving line flexibility and efficiency. The results show that the production cycle is reduced by 25.9%, the production line balance rate increases by 49.5 percentage points, the production efficiency rises by 10.3%, and the changeover time is cut by 91.6%.