Abstract: This article describes and analyzes the interference to geoelectric field and their typical variation characteristic in Changli seismic station,as well as analysis process.The result shows that there are mainly five types of interference:(1)thunder and rainfall,(2)bad contact of line,(3)DC interference,(4) polarized electrode,(5)fault of observation system.The variation characteristics of the five types of interference are different and depend on their own source.Therefore,we can judge them according to their variation characteristics.