433h。By using the DH5937 stress measurement system and sensor technology, the data of the bending moment and torque of the cutter shaft were simulated and measured, and a combined load spectrum of the bending torsion coupling of the cutter shaft was complied. Meanwhile, an estimated formula of the fatigue life of the cutter shaft bearing combined stresses was deduced by using Miner liner cumulative damage theory, and the fatigue life of the cutter shaft was estimated to be 443h longer than the designed life by using the load spectrum of bending torsion coupling.