Abstract: A new model was proposed to simulate the heat transfer in a semi-infinite saturated soil using a Green's function. In this study, the heat transfer performance in the surplus temperature filed was discussed. It illustrated that the most obvious temperatures response occurred at the walls of holes. The temperature would decrease exponentially with an increasing in the distance from the wall of the hole. The affected zone would increase with the spreading of thermal energy to the surrounding soil. In the case of multi-drilling holes, the spacing of hole had obviously affected the temperature at the wall of a hole. But the arrangement type of drilling holes had little influence on that. Two formulas were carried out to determine the optimal borehole spacing and the maximum effective depth, respectively. The results showed that it only affected the region close to the ground surface. The influencing zone would increase with increasing time. The largest influence depth was less than 20 meters and it had little influence on a constant temperature strata.