To investigate the low-cycle fatigue damage characteristics and life patterns of high-strength bolts used in assembled steel structures, a low-cycle fatigue test under constant-amplitude axial tension was conducted on 15 M24 Grade 10.9 high-strength bolts using a self-designed loading apparatus. The fatigue failure characteristics of typical high-strength bolt specimens under different displacement loads were analyzed. Additionally, the applicability of the power law function and the Coffin-Manson formula for predicting the low-cycle fatigue life of high-strength bolts was explored. The result shows that increased displacement load intensifies stress concentration in high-strength bolts, resulting in rougher fracture surfaces, reduced fatigue crack propagation area, and enlarged instant fracture area. The primary failure location of the bolts is at the first thread where the bolt and nut make contact. There is no significant monotonic relationship between low-cycle fatigue life of high-strength bolts and cyclic displacement amplitude, as similar fatigue life can correspond to different displacement loads. When the displacement amplitude approaches the ultimate load-bearing capacity, the bolt failure state resembles that of a static tensile failure. Furthermore, the power law function formula predicts fatigue life more accurately than the Coffin-Manson formula, especially when δ/δy is less than 2.45.