Abstract: In practical engineering, buried pipe is the form of well group. At present, there are two ways to calculate the heat transfer in a group of wells. One is to calculate the heat transfer of a single well, which is then directly multiplied by the number of holes to get the heat transfer of well group, without consideration of the thermal interference between wells. The other is the direct use of analytical solution or numerical simulation. The numerical solution of the powerful is good at calculating complex heat transfer problems, and can effectively grasp the dynamic heat transfer characteristics of buried pipe. The heat transfer space is large and the geometry configuration is complex, so the computation time is too long. In order to establish a heat transfer model of well group that can be quickly solved and used for thermal disturbance characteristics, the mixed solution heat transfer model based on analytical and numerical calculation is presented. The basic idea is to divide the space of the well group into the space inside borehole(including multiple drilling holes) and outside borehole taking the borehole wall as the boundary. Both steady-state analytical method and transient numerical heat transfer method are used to analyze the heat transfer characteristics inside and outside borehole respectively, and the 2 regions are coupled by the borehole wall temperature. After the establishment of summer conditions of single drill pipe heat exchanger test-bed, and the verification of single well heat transfer model, the FLUENT software in combination with the heat transfer model of well group is used to further study the wells at 3 kinds of special positions in the square well group(middle well, edge well and corner well), and the typical well group of physical model is determined and the thermal interference coefficient of the well group is defined. Finally, the thermal interference characteristics of the typical well group are studied mainly under the condition of continuous operation in summer. The research results show that with the development of heat exchanger of well group, the heat interference between wells in well group is generated and gradually increases, and at the same time the degree of heat interference for the middle of well is the largest, followed by the edge of well and the corner of well; due to the influence of heat interference, the heat transfer capability of the corner of well is the biggest and its borehole wall temperature is the lowest, the heat exchange ability and borehole wall temperature of the edge of well are in the middle, and the heat transfer capability of the middle of well is the minimum and its borehole wall temperature is the highest. After running for 90 d, the heat exchange of the corner of well is 6.5% more than the edge of well, and the heat exchange of the edge of well is 7.1% more than the middle of well; the contribution rate of heat exchange of the corner of well to the well group is gradually increased with the running time, that of the middle of well is gradually reduced with the running time, while that of the edge of well is basically unchanged.