Tianjin area is rich in geothermal resources and oil and gas resources. In 1990s, Dagang Oilfield Co., Ltd. built a large number of exploited wells for oil prospecting in Tanggu area. With the oil resource exhausting, most of the wells have been abandoned. Combined with geothermal geological datas and oil well configurations, the methods of transforming abandoned oil wells into geothermal wells is explored in this paper, the feasibility is proved through the successful transformation examples of T38-1 and T38-2 wells.