The fluorescence can be quenched by the hydroxyl radical produced by fenton reaction. The free radical scavenging activity of Rubus corchorifolius L. f. was determinated by mearsuring the change of fluorescence intensity of LGSF. The extracts scavenging rates are 27. 34%, 38.65%, 40.22 %, 41.68% respectively when extract's concentration is 0.40mg/mL,and free radical scavenging capacities of EtOAC extract is the best. A reference method was provided for reasonable exploit...