In the generation of ever-changing technology, the use of energy is increasing. Green buildings, smart grids, etc. are all required to use electricity. This study will focus on the analysis of the thermal performance of drilling U-tube soil heat exchangers and try to change the shapes and material of the pipes, then find out ways to increase the efficiency of the soil heat exchanger. The project will use the commercial software ANSYS Fluent to create geometric shapes and meshes, and use the Fluent solver to perform simulation calculations. Finally, the results will be imported into Tecplot for analysis and discussion. We maintain the cross-sectional area of the U-tube for fractal structures and change the material of the tube wall for better heat dissipation. According to the analysis of the simulation results, fractal star pipes have the lowest outlet temperatures in both the PVC material and the carbon steel material. And the star tube increasing the most heat transfer efficiency from the carbon steel material. The round pipe which use the carbon steel pipe, which the outlet temperature has been lower than the star tube using PVC material. So we can change the tube’s material to reduce the temperature in the tube except to the reference mentioned in the use of different backfill material.