Ubend Deep Borehole Heat Exchanger (UDBHE) has attracted much attention because it can effectively exploit deep geothermal energy and has high heat transfer performance. The thermophysical properties of mediumdeep ground generally change with depth, but there is a lack of indepth study on the influence of thermophysical properties of stratified ground on the heat transfer performance of Ubend deep borehole heat exchanger. Based on the UDBHE semi analytical heat transfer model established by the authors, the influence of thermophysical properties (thermal conductivity and volumetric heat capacity)of stratified ground on the heat transfer performance of UDBHE is studied. The results show that the thermal conductivity of each layer of ground has a great influence on the heat transfer performance of UDBHE, while the volumetric heat capacity of ground in each layer also has a certain influence, and the influence increases with the increase of ground layer depth. With the increase of time, the influence of ground thermal conductivity on the heat transfer performance of UDBHE gradually increases, while the influence of ground volumetric heat capacity on the heat transfer performance of UDBHE is basically unchanged. By keeping the weighted average values of the thermal conductivities of all ground layers constant, the heterogeneity of ground thermal conductivity has a great influence on the heat transfer performance of UDBHE, and the larger degree of heterogeneity of ground thermal conductivity would promote the heat transfer performance of UDBHE, otherwise it will inhibit the heat transfer performance of UDBHE. Similarly, the heterogeneity of volumetric heat capacity of ground also has a certain influence on the heat transfer performance of UDBHE, but its influence changes slightly with time. The research results provide important reference value for UDBHE performance prediction and optimization.