Abstract: The extract fromMagnolia grand if lora leavesw as iso lated by ethy l acetate and its main components w ereidentified by physical and chem icalm ethods. Its antiox idat ion activ ity w as detected and eva luated by two system s( DPPH?and lec ith in)w ith con tro ls for syn thetic an tiox idant PG ( propy l gallate) and natural antiox idan t PA ( phy ticacid) . The resu lts show ed that the extract conta ined f lavono ids and pheno lic compounds. W hen the ex tractw as d ilu??ted by 10 tim es( 92. 00mg?mL-1 ), its scaveng ing rate to H2O2 atta ined the h ighest, 29. 41% ; when itw as d ilu??ted by 20 t imes( 46. 00mg?mL-1 ), it had the h ighest activ ity to restra in ing act ive oxygen, 500 un its. The activ ityof tota l antiox idation from non??enzym e system w as 270 activ ity un its when the ex tract w as d iluted by 50 t imes ( 18.40 mg?mL-1 ). The resu lts o f appraisal by DPPH?and lec ithin systems show ed tha twhen the ex tractw as dilutedby 50 times( 18. 40mg?mL-1 ) , it had the best effect o f antiox idation w ith the highest scavenging rate to DPPH ??( 92. 69% ), wh ich w as h igher than PG and the restraining rate to lip id perox idat ion( 56. 67% ) w as as same as PA .Th is result prov ided scient ific basis for further approach ing and explo iting the b iolog ical act iv ity ofM. grand if lora.