Abstract: The mutual effect between hydrogel and fertilizer on physiological characteristics of photosynthesis of Photinia serrulata seedlings under water stress condition was explored by pot experiment. The following results were obtained: (1)Hydrogel and fertilizer had both their individual effect and the mutual effect on drought-resistance of the tested seedings, the variation of photosynthesis was mainly determined by water supply. The effect of fertilizer could be promoted under better water condition provided by hydrogel application, and the mutual effect between the hydrogel and fertilizer was beneficial to improving the net photosynthetic rates of seedlings in the experiment.(2)The mutual effect between hydrogel and fertilizer could significantly prolong the survival period and increase growth rate of the seedlings. (3)It was showed by determining the contents of Pro, MDA and the relative electrical conductivity of leaves that the mutual effect between hydrogel and fertilizer enhanced osmoregulation capacity of seedlings, which could alleviate water stress of the Photinia serrulata seedlings.