The quality of the geoelectric field data of Wenchang Wengtian station in Hainan Province has been declining since March 2019. The quality of the geoelectric field data has declined mainly due to the low daily correlation coefficient, the reverse change of the north-south long pole distance and short pole distance data curves, and the degree of insulation tends to a zero-level situation. From March 2019 to October 2020, we carried out detailed investigations and comparison experiments of electrodes and cables on the observation room installation system, outdoor and external lines, connection ports, etc., and carried out renovation of the cable line in October 2020. Starting from November 2020, the quality of the electric field data of the Wengtian station has recovered, the daily line relationship number has recovered to more than 0.8, the data curves of the six measurement channels have changed the same, and the insulation of the external line has recovered to more than 150 MΩ. After the experience of investigating the interference factors of the electric field data of Wengtian station, some methods have been obtained, hoping to serve as a reference for other stations that have installed geoelectric field instruments.