Abstract: Beijing as capital of China is located in North China. The geothermal field in Beijing is mainly medium-low temperature conductive type,in which the Wumishan Formation with a thickness of more than 2000m of the Jixian System is the main reservoir and the rock of the Wumishan Formation is dolomite. Conductivity of the reservoir was usually calculated to understand reservoir characteristics,which could not accurately reflect permeability of the reservoir due to density variation of geothermal water. In order to understand permeability of the reservoir to direct geothermal resources development,porosity and permeability data of 34 dolomite rock cores collected from field outcrop and down-hole were compared and analyzed. The results indicated that permeability of outcrop and down-hole ranges are (10.0001158～0.33333)10-3m2 and (0.0088～0.334)10-3m2 respectively,and the average value are 0.062232110-3m2 and 0.38531610-3m2. The porosity ranges from 0.25%to 3.00%. The permeability of the rock cores are so low that geothermal energy could not be exacted without factures and fissures generated from tectonic movement and karstification. Therefore,permeability calculated from pump test could reflect total permeability of rock matrix,fractures and fissures. The calculated permeability of reservoir from 110 pump tests ranges from 13.7410-3m2 to 104474.0010-3m2,and the average is 4797.5810-3m2. The cumulated percentage of permeability values between 10010-3m2 and 100010-3m2 are more than 75%,the values less than 10010-3m2 are only 13.64%,and the permeability values greater than 10000010-3m2 are 0.91 percent. In order to demonstrate relationship between reservoir buried depth and permeability,the buried depth were divided into 500m,500～1000m,1000～1500m,1500～2000m,2000～2500m,2500～3000m and 3000～3500m. The average permeability and average buried depth were plotted together in x,y coordinates. The results indicated that the average permeability of geothermal reservoir decays in the way of exponential with the increasing of reservoir buried depth,and R2 is 0.9415,indicating good correlation. The relationship between reservoir buried depth and permeability is significant in assessing potential of Wumishan Formation reservoir,calculating geothermal well depth accurately before drilling and reducing geological risks in Beijing.