Abstract:Approximately two days prior to the Ningqiang MS5.7 earthquake (May 27,2008), a large amount of cave strain anomalies were recorded in the NS and EW components at Baoji station. A previous study showed that these phenomena were short imminent earthquake precursors of the Ningqiang MS5.7 earthquake[1].By means of repeated earthquake tests and empirical statistics, the attribution of these anomalies was analyzed systematically to objectively verify the authenticity of this conclusion. Results showed that rainfall interference was the main cause of the remarkable strain anomalies.