Abstract: In order to determine best irrigation mode, it is necessary to research on water stress aftereffects to corn yield and senescence in the early corn growth stage. By pot and plot experiments, the results show that moderate rewatering after water stress in initial corn growing season can preserve large photosynthetic area, keep photosynthetic system activity, delay chlorophyll degradation and enable functional leaves to maintain high photosynthetic efficiency, which is eventually beneficial to dry matter accumulation during final growing season of corn. It proves that the post-drought rewatering in the initial corn growing stage has obvious aftereffects. Particularly, the aftereffects are significant after water stress at late stage of seedlings and short-duration light drought at early jointing stage.