High-pressure reactors are subjected to alternating pressure and temperature loads over long periods. Hidden fatigue microcracks are prone to develop in the shell and welds, which cannot be detected by conventional visual inspection. This can easily lead to high-pressure cracking, media leakage, and other safety accidents. Our factory has abandoned a single testing method and adopted a practical testing approach combining hydraulic pressure testing and acoustic emission detection to accurately predict potential fatigue cracks in the shell. Through progressively increasing hydraulic pressure testing, the overall pressure-bearing capacity and structural stability of the equipment are verified. Simultaneously, acoustic emission detection equipment is used to capture stress signals indicating the propagation of microcracks inside the shell under high-pressure loads, accurately locating hidden defects and assessing the extent of crack propagation. The entire testing solution covers the shell, longitudinal and circumferential welds, head transition zones, and stress concentration points in the nozzles, identifying fatigue defects missed by conventional flaw detection. The test data is accurate and traceable, complying with the periodic inspection standards for special equipment. It allows for early prediction of equipment aging and cracking potential, enabling timely maintenance and rectification, preventing operation with faults, and ensuring the long-term safe service of high-pressure equipment.