Abstract: High strength bolt is the important fastener of automobile and steel structure and its quality directly affects the safety and reliability of the automobile and steel structure. After treatment process such as quenching and tempering, cracks occur in bolt. In the process of installation and using, bolt undertakes complicated stress. So the cracks (especially cracks in bolt root) will finally cause failure and fracture of bolt , which have serious consequence in use. A bolts scanning testing imaging system based on the eddy current array probe was introduced, which specializes in high strength bolt root crack detection. The system could effectively detect the cracks in bolt root so as to prevent the accidents happen. Compared to traditional mechanical rotary bolt eddy current testing system, this system could detect the circumferential crack quickly in lower mistaken rate, and with larger scan coverage, the system has simpler mechanical device. Using real time scanning testing imaging system is also a good solution to mass parts detection.