Abstract: The functions of paddy fields will shift from mere production to incorporate with ecological functions The retained water in paddy fields during fallow period can not only maintain ecological function,but also enhance soil moisture and recharge groundwater in field.In this paper,the sand tank model is used to investigate the effects of groundwater recharge with sand piles on solute transport in fallow croplands.The results show that the infiltration rate increases about 40 times with the sand piles piercing through hard pan than without sand piles.On the contrary,the sand piles also increase the solute transport rate between soil layers The effects are more conspicuous when the sand soil exists under hard pan.Therefore,the quality of irrigation water has to be inspected during retained process to prevent the soil and groundwater from being polluted.