Effects of regulated deficit irrigation（RDI） at seedling stage of maize on plant characters,photosynthesis rate and yield were investigated with pot-cultivated maize.The results indicated that plant height,stem thickness,leaf area and dry weight of crown and root reduced by RDI at seeding stage.But root length and ration of root/shoot increased.Photosynthesis rate determined at filling stage was increased in slight and medium RDI,but it decreased in severe RDI.Water use efficiency was higher in all treatment com-pared with the control.Yield was increased by 1.90% in medium RDI,but it decreased by 1.47% and 6.58% in slight and severe RDI.When water content was 50%,growth of maize was retarded but rooting was improved.As the yield was not significantly affected,it does not need irrigation.