Abstract: According to the operating principle of the deep borehole heat exchanger（DBHE）combined with geothermal wells,an unsteady state heat transfer model coupled inside and outside of the borehole is established,based upon the modified thermal resistance and capacity model of the coaxial pipe and the thermal and mass transfer theory in the geothermal reservoir.The mathematical model is validated by the experimental data obtained from a field test which is carried out based on the DBHE combined with geothermal wells in a demonstration project.Based on the dual-continuum spatial coupling approach,a sensitivity analysis is performed to examine the effect of typical parameters on the heat transfer performance of the DBHE.The simulated calculation indicates that the average heat exchange power of the DBHE increases respectively 75 k W and 108 k W,when the quantity of geothermal water exploitation increases from 0 m~3/h to 75 m~3/h and 150 m~3/h.The results show that the heat transfer mechanism is changed in the geothermal reservoir and the heat transfer process of the DBHE is intensified through orderly regulating the quantity of geothermal water exploitation and the well distance.However,the increasing rate of the average heat exchange power of the DBHE decreases significantly while the quantity of geothermal water exploitation increases,meanwhile the sensitivity of the DBHE depth and the quantity of circulating water on the heat transfer performance of the DBHE reduces.