In Kin-men district, the rate of ground water usage is very high due to the congenital lack of surface water resources. The water used for domestic purpose accounts for more than forty-five percent of total public water supply. Therefore, it is important for the government agencies to keep track of the ground water quality. In this research, extensive hydrologic and geologic data of Kin-men district were collected. By using the DRASTIC model established by United States Environmental Protection Agency (USEPA) in association with American Well Association, the contamination potential index of ground water in Kin-men is established. The results could be used as a basis for establishing a ground water monitoring program. Fifteen locations with highest DRASTIC scores are suggested as the first-priority sites for installing ground water monitoring wells. In addition, risk assessment done by incorporating additional information on the land development conditions could also be used to set up wellhead protection program in the future.