Abstract: In order to study the nature and effect of interference fields of high voltage power lines on earth resistivity observation,we carried out observations of high voltage interference fields for 220103V,110103V,35103V and 10103V power lines respectively at 14 site in Shandong,Henan and Liaoning provinces. We obtained some knowledge about the nature of high voltage interference fields and pointed out their characteristics in frequency,spatial distribution and controlling factors Meanwhile,by numerical fitting computation,a mathematical expression describing the spatial distribution of high voltage interference field is obtained,thus providing a scientific basis to eliminate its effect. On the basis of the above study,some methods to eliminate the high voltage interference are suggested.