The Apillm graveolens L. variety of ‘Queen’ and the self-made nursery matrix(Caragana powder∶perlite∶vermiculite=7∶2∶1 by volume) as test materials,plugs of different size(32 cells to 288 cells/plate) were used to nurture seedlings.The effects of volume size of the root domain on A.graveolens L. seedlings growth,gas exchange and chlorophyll fluorescence induction kinetics curves under the conditions of Caragana mixed matrix were investigated to provide the scientific basis for nurturing vegetable seedlings with Caragana mixed matrix and the resource utilization theory of Caragana.The results showed that:(1)A.graveolens L. plant height,leaf number,root length,root volume,shoot fresh weight,shoot dry mass,root fresh weight and root dry weight reduce with the decrease of volume of the root domain.(2)Net photosynthetic rate and transpiration rate of 110.07 cm³/hole were higher by 64.13% and 18.87% than that of root volume 7.28 cm³/hole;(3)Stomatal conductance reduced with the root domain volume decreases,intercellular CO₂ concentration was not much affected by the root domain volume;Root domain too large (110.07 cm³/hole) or too small (7.28 cm³/hole) would affect the PSⅡ photosynthetic electron transfer.When the root domain volume was 25.68 cm³/hole,φ_Eo value reached the maximum,when the root domain volume reached 14.34 cm³/hole,ψ_o value was the maximum,when the root domain volume was 17.32 cm³/hole,TR_o/CS value reached maximum;when the root domain volume reached 19.21 cm³/hole,ET_o/CS value was the maximum.Therefore,the A.graveolens L. seedlings gas exchange and chlorophyll fluorescence parameters change were directly affected by the root domain volume,and then affecting the photosynthesis and growth of the seedlings.