Crop yield and water use efficiency(WUE)in a wheat-maize double cropping system are influenced by short and unevenrainfalls in the North China Plain(NCP).A 2-year experiment was conducted to investigate the effects of irrigation on soilwater balance,crop yield and WUE to improve irrigation use efficiency in the cropping system.Soil water depletion(△SWS)by crop generally decreased with the increase of irrigation and rainfall,while △SWS for the whole rotation was relativelystable among these irrigation treatments.High irrigations in wheat season increased initial soil moisture and △SWS forsubsequent maize especially in the drought season.Initial soil water influenced mainly by the irrigation and rainfall in theprevious crop season,is essential to high yield in such cropping systems.Grain yield decreased prior to evapotranspiration(ET)when ET reached about 300 mm for wheat,while maize showed various WUEs with similar seasonal ET.For wholerotation,WUE declined when ET exceeded about 650 ram.These results indicate great potential for improving irrigation useefficiency in such wheat-maize cropping system in the NCP.Based on the present results,reasonable irrigation schedulesaccording to different annual rainfall conditions are presented for such a cropping system. Crop yield and water use efficiency (WUE) in a wheat-maize double cropping system are influenced by short and uneven drainage in the North China Plain (NCP). A 2-year experiment was conducted to investigate the effects of irrigation on soilwater balance, crop yield and WUE to improve irrigation use efficiency in the cropping system.Soil water depletion (△ SWS) by crop generally decreased with the increase of irrigation and rainfall, while △ SWS for the whole rotation was relatively stable among these irrigation treatments. High irrigations in wheat season increased initial soil moisture and △ SWS forsubsequent maize especially mainly in the drought season.Initial soil water influenced mainly by the irrigation and rainfall in the pre- crop season, is essential to high yield in such cropping systems. Grain yield decreased prior to evapotranspiration (ET) when ET reached about 300 mm for wheat, while maize showed various kinds of WUEs with similar seasonal ET. For wholerotation, WUE declined when ET exceeded about 650 ram.These results indicate great potential for improving irrigation useefficiency in such wheat-maize cropping system in the NCP. Based on the present results, reasonable irrigation schedulesaccording to different annual rainfall conditions are presented for such a cropping system.