Abstract: A DPPH-Microplate assay was made to determine the free radical scavenging activity in leaves of subtropical plants of garden and afforestion belonging to 83 Families 164 Species. The results showed it can be divided into three types of high (sample concentration of scavenging 50 percent of DPPH free radical IC₅₀ < 0.500 mg ·mL ^-1) , medium ( IC₅₀0.501 - 1.000 mg·mL ^-1 ) and low ( IC₅₀ > 1.001 mg·mL ^-1) free radical scavenging activity. There are 25 with high activity , 31 with medium, 108 with low. Among them, Pomegranate, Chinese Witchhazel, Beautiful Sweetgum, Buerger Maple, Chinese Loropetalum, Puberulous Glochidion , Sylvestral E2-aeocarpus , Blue Japanese Oak , Japanese Kerria and Common Nandina have the highest activity.Their IC₅₀ are 0.283、0.292、0.312、0.326、0.345、0.369、0.379、0.389、0.398、0.403 mgmL^-1,respectively.Others IC₅₀ is between 0.401～14.300 mg·mL ^-1 . It is suggested that these species can be used a new resource of free radical scavenger and antioxidant products.

Key words: Subtropical plants of garden and afforestion, 1 ', 1-diphenyl-2-picryhydrazyl (DPPH), Free radical scavenging activity