To investigate the composition and antioxidant activity of Brasenia schreberi,the system pre-experiment method was used to conduct pre-experiment on the possible chemical components of the separated portions with different polarities,and explored the chemical composition of each part in this experiment.Organic extraction method was used to extract water,ethanol,n-butanol,and ethyl acetate to obtain four different polar extraction parts,and the Folin-Ciocalteu colorimetric method was used to determine the total phenol and flavonoid in four extraction parts;DPPH,ABTS and FRAP methods were used to analyze the preliminary antioxidant activities of the four extracts.The results indicated that the polyphenol content in the four extracts were,ethanol,water,n-butanol and ethyl acetate,from high to low.The results showed that the extracts of different polar solvents of B. schreberi had antioxidant activity,among which the ethanol phase had the best antioxidant activity.The EC₅₀ of scavenging ABTS and DPPH free radicals were 0.133 and 1.526 mg/mL,respectively.The highest content of total polyphenol in the ethanol phase was 28.045 mg/g DW.The total polyphenol content was correlated with ABTS,DPPH free radicals and total reduction capacity(r=0.961,0.960,0.997).The polyphenols in the extracts of B. schreberi may be the main antioxidants.