Abstract: Heat distribution pipeline used in city heating would inevitably produce aging corrosion leakage, even cause safety accidents. Both domestic and international scholars pay more attention to the study of non-destructive testing. In this paper, we developed the research on trenchless detection of the parallel heating pipelines' corrosion defects based on the basic principle of pulsed eddy current. By using simulative actual working condition, we collected the pipeline's induced electromotive force signal, and established the relation model between induced electromotive force and pipeline wall thickness. Furthermore, on the basis of this model, we calculated the parallel heating pipeline's wall thickness values. According to the change of wall thickness, corrosion defects were located. This study proposed a feasible method for detection of city parallel heating pipelines' corrosion defects, and has good practical values in engineering.