Abstract: In order to study on effect of different stages of root cutting on growing dynamic of peanut, provide theoretical basis for the reasonable stage of root cutting. A field experiment under mulching was conducted to study the effect of different stages of root cutting on growing dynamic of peanut. The results showed that, root cutting could reduce the plant height, number of leaves and branches, number of flowering and needles per plant of peanut, the earlier cutting the root, the more obvious effect was. The reasonable stage of treatments was helpful to delay leaf senescence in peanut, maintain the suitable leaf area index for a long time, increased the effective number of branches needles and less useless dry matter accumulation, reduced the excessive growth redundancy, in favor of pod formation; Later treatments caused minor damage to roots of peanut; there was little effect on redundancy reducing and compensation effect. In this experiment, the fifteenth day to the twentieth day after flowering of root cutting could obtain the best effect on plant growth.