Abstract: The conventional online detection method for leakage current of overhead contact line insulators mainly uses ESDD to extract leakage characterization, which is easily affected by changes in current amplitude characterization, resulting in high leakage current detection deviation. Therefore, a new online detection method for leakage current of overhead contact line insulators based on EMD feature recognition is proposed. By utilizing EMD feature recognition to process insulator leakage current detection signals, analyzing the frequency domain characteristics of contact line insulator leakage current, online detection of insulator leakage current has been completed. The experimental results show that under different numbered insulators, the leakage current detected by the designed online detection method for contact network insulators is close to the actual leakage current, with small deviation and good detection performance. It has certain application value and has made a certain contribution to solving the safety problem of contact network insulators and reducing the difficulty of contact network operation and maintenance.