Abstract: Based on Environment Fluid Dynamic Code (EFDC) Model, the concept of water age is used to study the effect of tide and wind on the water exchange time in Haizhou bay and adjacent regions. The results show that the range of the average water age is -48.5%~18.4% under annual statistics wind. The summer wind is in favor of the water exchange, and the water exchange time under summer wind conditions is 36.3% less than that under the tidal force condition only. However, the winter wind slows down the water exchange, and the water exchange time under winter wind conditions can be 40.8% more than that under the tidal force condition only. The study shows that the water exchange in open sea area is significantly affected by the monsoon, and the seasonal changes of the water exchange well explain the dynamic mechanism of the seasonal changes of the pollutant distribution.