The heat exchange tubes of the steam generator, as a key component of the pressure boundary in the primary circuit of the high temperature gas-cooled reactor nuclear power plant, plays an important role in heat exchange and radiation barrier, and its structural integrity seriously affects the safe operation of nuclear power. In response to the in-service detection difficulties of this type of special structure heat exchange tubes, a dedicated electromagnetic ultrasonic guided wave automatic detection system has been designed, a magnetic field enhanced electromagnetic ultrasonic guided wave probe with builtin single point detection has been developed, a five axis linkage multi degree of freedom automatic transport device with modular components has been developed, a dynamic positioning method for tube holes based on machine vision has been proposed, a full-scale simulation test platform for steam generator was established, and positioning accuracy test and defects detection test were carried out. The experimental results indicate that the designed automated detection system can achieve high-precision positioning and automatic walking of target tube holes at any position, and can identify the notch defects at the weld of dissimilar steel and about 60 m away from the detection end on the simulator. The effective detection range covers the entire length of the heat exchange tubes, which is expected to provide technical support for the quality and health evaluation of the special structure heat exchange tubes of the steam generator in high temperature gas-cooled reactor nuclear power plants.