Abstract: The environmental behaviour,bioconcentration of rare earth elements and their effects on animal gonad were studied by means of radioisotope tracer.The results indicated:(1)The ¹⁴⁷ Pm ¹⁴¹Ce and ¹⁴⁷ Nd had strong adsorptivity in soil.So,they were hard to transfer and accumulate easily in soil.When in water body,they accumulated in sediment.(2)All the organisms under study showed apparent ¹⁴⁷ Pm concentrating capabilities.(3)The residues of ¹⁴⁷ Pm ¹⁴¹Ce and ¹⁴⁷ Nd were unevenly distributed in the animal′s viscera and tissues.But,higher residues were found in bone,marrow,eye,brain,heart,adipose and testis,and their concentration increases with dosage and time,which shows selective accumulation.There were much higher concentration of RE in bone than in other viscera and tissues,and ¹⁴¹ Ce is the highest in eye.(4)With intraperitioneal dosing of Nd or Ce being 200 mg·kg ^-1,the gonadial hormone(testosterone or progesterone) concentration in the serum decreased significantly as compared with the control,showing apparent inhibition on gonadial hormone secretion in mice.However,with different dosages of Ce,200 and 800 mg·(kg·d) ^-1 added in feed,the testosterone concentration in serum made no significant difference,but the malformation rate of spermatozoon proves higher,and increased with feeding time and dosage.Based on the primary exploration on safety of agricultural use of RE for eco-environment,some suggestions are brought forth.