Abstract: Aiming at the problem that the traditional inner coating detector is limited to the detection of unwelded pipe sections and large-diameter pipes, a detection system for damaged points of inner coating based on pulsed electric spark was developed. To meet the requirements of the detection distance on-site, a pneumatic pump is used as the power source, and a power valve structure is designed to ensure that the detection distance can reach more than ten kilometers. For the actual situation that the pipe diameter is only 8 cm, the detection system is designed into four sections. Each section is installed with a miniature pulse transformer, miniature pulse high voltage drive circuit, miniature main control circuit, and high capacity lithium battery. The results of the joint debugging of software and hardware show that the detection system is reliable and stable, and can automatically detect weak pulse currents and identify damaged points of the inner coating, and has the characteristics of long detection distance and compact structure.