More and more high voltage direct current transmission(HVDC)lines are put into operation in China,which has great affected the observation quality and application research of geoelectric field observation data. Based on the influence mechanism of HVDC interference on the observation of geoelectric field,we take Jiangsu Province as a study region,analyze and summarize the influence characteristics of HVDC transmission lines on the observation data of geoelectric field in the past five years in the study areas. The relevant conclusions are as follows:① When the observation data of geoelectric field are interfered by HVDC transmission lines,the geoelectric field will be distorted for a period of time,then the unbalanced current disappears and the data returns to normal. ② The direction of the distortion of geoelectric field is related to the layout of the observation station and the relative position of the earth electrode and the observation station. ③ The ground electrode of HVDC transmission lines are far away from Jiangsu geoelectric stations,and the ratio of the variation amplitude of the long and short polar distance observation data affected by the same HVDC transmission line in the same direction of the same station is close to 1. ④ Even though the amplitude of geomagnetic interference is same in the same station,the variation amplitude of the geoelectric field data in the same station is not necessarily the same,which is related to the conductivity change of the underground electrical structure between the station and the ground electrode. Our above results is of significance for the fast discrimination of HVDC lines,the abnormal implementation of data,and the application research of geoelectric observation data.