To provide a theoretical basis for soil phytoremediation by direct planting in cadmium-contaminated areas,through hydroponic test,WinRHIZO 2016 root measurement and analysis software,Coomassie brilliant blue G-250 staining,thiobarbituric acid method,guaiacol method,NBT photoreduction method,atomic absorption spectrophotometer method were used to study the effects of different mass concentrations of Cd(0,0.3,3.0,20.0,60.0,120.0,180.0,240.0 mg/L) on seed germination,seedling tolerance and enrichment of Cosmos bipinnata.The results showed that 0. 3 mg/L Cd stress could promote seed germination and seedling growth of Cosmos bipinnata but not significantly.The stress of 3.0 mg/L Cd had no significant inhibitory effect on the seed germination of Cosmos bipinnata, and significantly inhibited the growth of seedlings. 240.0 mg/L Cd stress completely inhibited the seed germination and seedling growth of Cosmos bipinnata.The effect of Cd stress on the bud length inhibition index of Cosmos bipinnata seed lings was significant.The effect of Cd stress below 60.0 mg/L on the root length inhibition index of Cosmos bipinnata seedlings was significant.The resistance of Cosmos bipinnata to Cd was stem>root.Cosmos bipinnata seeds reached the limit mass concentration of germination under 254. 225 mg/L Cd stress.With the increase of Cd stress concentration,the soluble protein content of Cosmos bipinnata seedlings increased first and then decreased,the content of malondialdehyde decreased first,then increased and then decreased.Peroxidase activity decreased first,then increased and then decreased,superoxide dismutase activity decreased first,then increased and then decreased.The Cd uptake of Cosmos bipinnata seedlings increased with the increase of Cd stress concentration.When the Cosmos bipinnata seedlings were stressed by 180.0 mg/L Cd,the Cd content in the seedlings was 47.83 mg/kg.Cosmos bipinnata grew normally under Cd stress of 3.0 mg/L,and could withstand Cd stress of 180.0 mg/L,so the seeds had strong ability to resist Cd stress.