Abstract: In order to meet a high efficient recovery and utilization of the air retuning low temperature waste heat in a coal mine, a reconstruction optimization was conducted on diffusion tower of the counter rotating main fan. On the premise to ensure a good aerodynamic performance of the fan, the heat and humidity exchange V olume of the diffusion tower was increased. a fluid simulation method was applied to simulate and study the internal flow field condition before and after the reconstructi on of the diffusion tower and to simulate and study the air and liquid phase flow heat and humid exchange effect within the diffusion tower of the spray- raining heat exc hanger. Based on a coal mine in Shanxi Province as an example, an engineering verification was conducted on the numerical similar simulation results. The results sho wed that after the reconstruction, the similar simulation results of the temperature differences between the income and outcome medium temperature difference at the s pray- raining type heat exchanger was 3 ~ 7。C，which could fit with the actual engineering operation ( the average temperature difference of the actual measured in mo st cold month was 5 °C) and after the reconstruction, the heat recovered volume of the mine spray raining type mine heat recovery system could meet the winter heat re quirements of the freezing prevention.