Abstract: A systematic study on additive-subtractive hybrid manufacturing (ASHM) is conducted to address the dual requirements of manufacturing accuracy and structural reliability for steam turbine blades operating under high-temperature and high-pressure conditions. 316L stainless steel is used as the material, and five-axis integrated hybrid manufacturing equipment is employed, combining laser powder-fed additive manufacturing with CNC subtractive machining to achieve near-net-shape forming and precision machining in a single process. The adoption of a flipping additive strategy and a double-end clamping scheme improves machining rigidity and material utilization. Combined with path simulation, online monitoring, and Monte Carlo stochastic simulation, the process reliability is quantitatively analyzed. The results indicate that this process can increase additive efficiency by 25%-30%, control geometric errors within ±0.03 mm, achieve surface roughness Ra better than 0.4 μm, and maintain a fatigue life reliability above 0.96. The coupling relationship between additive-subtractive parameters and structural reliability is revealed, verifying the high-precision and high-reliability advantages of hybrid manufacturing for complex thin-walled components. Theoretical and technical support is provided for the efficient manufacturing and remanufacturing of steam turbine blades.