Abstract: Bolted connection is one of the most widely employed fastening connections in industrial equipment. The fatigue reliability of bolted connection is critical to the operational safety of service equipment. This study integrates macroscopic experimentation with microscopic analysis to investigate the axial fatigue performance conducted on Class 8.8, Class 12.9 bolts, and Class 10.9 stud bolts. Comparative fatigue tests were conducted on bolts made of the same material but processed via cutting and rolling techniques. Additionally, axial fatigue tests were carried out on simulated bolted joint structures, and ultrasonic preload monitoring equipment was utilized to track changes in bolt preload. Experimental results indicate that the fatigue performance of Class 8.8 bolt is obviously better than that of Class 10.9 and 12.9 high-strength bolts. The fatigue failure life of Class 8.8 bolt is more than 10 times that of Class 12.9 bolt when they are subjected to the same fatigue load amplitude. The thread of Class 8.8 bolt is machined by the rolling process, while the threads of Class 10.9 and 12.9 bolts are machined by the cutting process. The test results of bolts made from the same material but processed by different methods reveal that the fatigue life of bolts machined by rolling process can be prolonged by 5~10 times. Under the same fatigue load level, the fatigue life of the fastener is over 7 times longer than that of the simulated connection structure.