The grounding grid fault diagnosis based on the surface potential distribution needs a large amount of measured data. To reduce the workload in field test and improve the calculation accuracy of surface potential of grounding grid

this paper presents a method for calculating the surface potential distribution of grounding grid based on the echo state network. First

the echo state network is trained according to the numerical results of sur-face potential distribution of grounding grid. Then

the grounding grid is divided into several sections according to its structure. Finally

a small amount of field test data is put into the echo state network to obtain the surface potential distribution of the whole grounding grid. Calculation results and the experimental results of a grounding grid model show that the proposed method is capable of obtaining calculation model of the surface potential distri-bution at a specific mesh of grounding network

hence the surface potential distribution of the grounding grid can be calculated accurately and the workload in field test can be reduced significantly. The result could provide a theoretical basis for the fault diagnosis of grounding grid based on surface potential distribution.