The forest has the ability to conserve water and also play an important role on purifying rainwater.Rainwater is filtered through various forest layers such as canopy and litter before entering surface water,and then further filtered by soil layers during the transportation process to ground water.This combination of forest and soil layers usually can produce the maximum hydrological function of forest ecosystems.Based on the principal of systematics,the study of the dynamic characteristics of lead(Pb)and cadmium(Cd)in evergreen broad-leaf forest ecosystem was conducted in Simian mountain,Chongqing.Study presented herein aims to realize the fate and transport of Pb and Cd in evergreen broad-leaf forest ecosystem,and understand the effect of this ecosystem on rainfall purification,and know well the irreplacable ecological role played by the forest area.The results show that the average concentrations of Pb and Cd in precipitation were 22.95μg/L and 2.71μg/L,respectively.Both the canopy and litter layers of the evergreen broad-leaved forest ecosystem have a purifying effect on Pb and Cd in wet deposition,however,the purification capacities of each layer were significantly different.The relative interception amounts and retention rates of forest canopy,litter and soil layer were 20.15μg/L,1.04μg/L,-0.12μg/L and 88.08%,4.54%,-0.51%for Pb,and 2.19μg/L,0.35μg/L,0.04μg/L and 80.81%,12.89%,1.44%for Cd respectively.The evergreen broad-leaved forest ecosystem have strong retention capacity on Pb and Cd,the overall retention rate on Pb and Cd was 91.82%and 95.09%,respectively.The interception capability in each layer was decreased with the order of canopy >litter > soil.