Abstract: A three-dimensional unsteady state numerical model is optimized for the simulation of heat transport in aquifers which is evolved from borehole heat exchangers（BHEs）. Moreover,an analytical model including thermal dispersion is developed to calculate the excess temperature in aquifers. Combined with the thermal response experiment in the seepage sandbox,the analytical model is probed into the influence of thermal dispersion on heat transfer characteristic and the thermal effective radius in aquifers. Considering the effect of thermal dispersion,analytical solutions of excess temperature at each observation point are favorable similarity with experimental results. The root mean square error of excess temperature RMSE（Θ）are less than 3% between calculated results and test results. The calculation indicated that the influence of thermal dispersion on the evolutionary process of the temperature field in aquifers have the characteristic of space-time inconsistency. When the heat transfer process tends to steady state,the rate and magnitude of the excess temperature change increases significantly in the region of BHEs while the thermal dispersion increases. However,the magnitude of the excess temperature change decreases gradually in the downstream area of BHEs which the thermal effective radius is reduced.