Background:The study aimed to obtain data on the effects of cultivation and soil reduction of green manure crop on the quantity and quality of organically cultivated Cynanchum wilfordii Hemsley.Methods and Results:The experiment comprised four treatments: control, hairy vetch, barley, and hairy vetch + barley (3 : 2). The plant height in the hairy vetch treatment (86.3㎝) was significantly different from that in the other treatments, whereas the stem diameter leaf area, and special product analysis division (SPAD) value did not differ across the treatments. The largest soil reduction of green manure crop was recorded in the barley treatment (440 ㎏/10 a), whereas the smallest was recorded in the single treatment with hairy vetch (80 ㎏/10 a). The hairy vetch + barley (60 : 40) treatment showed 63% more soil microorganisms than control. Radical scavenging activity estimation revealed that the total polyphenol content was highest (1,740 ㎎/㎏), and the 2,2-diphenyl-1-picrylhydrazyl (DPPH) was 92.6% in the barley treatment. The 2,2’-azino-bis-(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) activation was highest in the control (51.1%), and the root yield was the highest in the barley treatment (310 ㎏/10 a).Conclusions:The root yield, total polyphenol content, and antioxidant activity of Cynanchum wilfordii (Maxim.) Hemsley increased in presence of the green manure crop barley.