Abstract: Partial discharge detection and location of indoor electrical equipment is an effective means to ensure the long-term stable operation of equipment, and the accuracy of time delay estimation is an important factor affecting the accuracy of partial discharge detection and location of indoor electrical equipment. In order to solve the problem of delay estimation accuracy of partial discharge signal under the influence of noise and multipath effect, a preprocessing method of partial discharge signal based on double EEMD decomposition and reconstruction is proposed in this paper, which effectively improves the signal-to-noise ratio of partial discharge signal and the accuracy of delay estimation algorithm. Simulation and experimental results show that the proposed method can effectively improve the accuracy of time delay estimation compared with the generalized cross-correlation algorithm, and the proposed algorithm is more stable and robust. The proposed method is used to accurately estimate the time delay of partial discharge signals in indoor environment with low SNR and obvious multipath effect.