Abstract: The results of the four trials to determine the effects of different defoliation treatments on radish (Raphanus sativus var. longipinnatus) yield are presented in this study. Four defoliation levels of 0(control), 33, 66 and 100% were applied at 5-leaf stage. The results demonstrate that the net photoassimilate rate, root/top ratio, relative growth rate of root and leaf, and economic coefficient after defoliation was reduced, and a close relationship between yield reduction and the defoliation treatment was observed. From the results of the experiment, it is found that defoliation treatment had a significant affect on the growth and yield of radish plants.