Abstract: This paper summarizes several interference events of HVDC transmission in Shaanxi geoelectric field observation, and analyses the variation characteristics and causes of interference. It is considered that the geoelectric field observations at five stations in Shaanxi Province are all disturbed by HVDC transmission, and the sources of interference are mainly from four HVDC transmission systems. The degree of interference from HVDC transmission system varies from station to station. There are two kinds of interference modes:ground current interference and line synthetic electric field interference. The feasibility of detecting the stability and correctness of the geoelectric field observation system by using the interference characteristics of HVDC transmission to the geoelectric field is discussed. A method to determine the fault of the observation system and the abnormal electrical parameters of the underground medium is proposed. Finally, some suggestions for identifying and dealing with HVDC transmission interference are put forward.