The safety status of bolts in critical components of hydraulic turbine units is fundamental to ensuring long-term stable operation. A monitoring system enabling full-coverage stress detection with minimal sensors was established by integrating finite element analysis and ultrasonic online monitoring technology to efficiently monitor axial stress in head cover bolts. A holistic finite element model of a hydraulic turbine head cover from a power plant was developed to analyse axial stress distribution characteristics. Real-time data from a multi-channel monitoring system validated the reliability of the simulation-based sensor placement strategy. The results demonstrate that the bolt group exhibits significant non-uniform stress distribution, with stress mutations induced by transient water hammer effects during start-stop operations. This research proposes a novel simulation-driven and data-verified integrated methodology for analysing dynamic load transfer mechanisms in critical bolts, providing analytical frameworks and strategies for condition monitoring of key components in hydraulic turbine systems.