Abstract: According to the drop size affected to the water saving and heat exchanging efficiency during the operation process of the spraying heat exchanger in th e mine air retuning roadway, the Fluent software was applied to study the relationship between the drop size and drop escape rate, drop collection rate, average temper ature of drops under the heat exchanger, total heat transfer value between the air retuning and drop, and air retuning temperature at the outlet of the heat exchanger.Th e results showed that when the drop diameter was selected ranging from 0.10-0.15 cm, the heat exchanging efficiency of the heat exchanger would be bester and the dr op escape rate would be lower, water saving efficiency would be higer.