The study site of this paper located in Dongyang landslide area at Fongyuan district, Taichung city of Taiwan, was surveyed by using geological boring, salt logging, inclined tube, and earth electrical logging methods in order to understand the characteristics of stratum and groundwater distribution. Four locations of boring well were selected to carry on the salt logging investigation. This research tried using earth electrical logging to match up the local situation and geological drilling, and to analyze the geological stratum and indicate the sliding surface. The depth of each boring well was 30m. After analyzing, investigations of salt logging and inclined tube, could found the distribution of groundwater flows and which may located in the failure surface exactly.