The common changes in the continuous observation of the apparent resistivity observation includes annual change,daily change,step,high frequency disturbance,quick drop/rise,annual persistent decrease/rise change and etc. Variety of vibration forms often overlay together constituting a complex variation shape in the observation curve. Tin this paper we analyze and summarize the possible causes of usual variations in the apparent resistivity observations,by combining the basic principle of apparent resistivity observation,the results from theoretical researches and experiments,and anomaly verification work of geoelectrical disciplines,in order to provide a reference for the abnormal analysis and earthquake tracking.