Abstract: In order to clarify the effects of different concentration Se treatments on the growth,development,photosynthesis and the primary metabolism of plant,Astragalus adsurgens,with high Se accumulation capacity under hydroponic condition was used as material.The results showed that different concentrations of Se had different effects on the growth and development of A.adsurgens.Low concentration Se treatment(5μmol·L^-1)significantly promoted the growth of A.adsurgens,whereas high concentration Se treatment(100μmol·L^-1)had the opposite effect.The content of Se in roots and shoots was positively correlated with the treatment concentration,and the transport coefficient of Se in A.adsurgens decreased gradually with the increase of selenium concentration.The results of photosynthetic pigment content and leaf chlorophyll fluorescence parameters showed that low-concentrations of Se promoted photosynthesis of A.adsurgens,while highconcentrations of Se significantly inhibited it,the Se transport coefficient under 100μmol·L^-1treatment decreased by 83.5%compared with 5μmol·L^-1treatment.After detection and analysis of primary metabolites,it was found that low concentrations of Se up-regulated the metabolic pathways related to amino acid metabolism in plant roots and shoots,while high concentrations of Se mainly up-regulated the metabolic levels of primary metabolites that were closely related to the synthesis of secondary metabolites.Our results showed that treatment with low concentration of Se increased the photosynthesis level of A.adsurgens and the level of primary metabolism related to growth,and promoted plant growth;treatment with high concentration Se increased the level of A.adsurgens by reducing the transport of Se to the ground and more primary metabolites for the synthesis of secondary metabolites were used,and the tolerance of plants to Se stress was improved.