Abstract:Nicosulfuron is an important herbicide used for maize. The sensitivity of 32 maize varieties to nicosulfuron was studied and this result could provide some warranty for using of nicosulfuron. With the method of planting in pot, the effect of nicosulfuron to maize in seedling was observed. The results showed that with the normal dosage 60g/hm2, inhibiting rate of the plant height and weight of Taiyu 2 (zhengjiao), Jinzhenzhu, Taiyu 15, Zinuo and other three breeds are beyond 40.4% and 31.37%, and it is obvious that plant growing is inhibited, the leaves etiolate and new leaves twist severely and couldn’ t grow normally. Inhibiting rate of the plant height of Ziyu 2, Taiyu 2 (fanjiao), Liaoyu 18, Luyuandan 33, Zhengdan 958 and some other varieties are between 30.6% and 38.1%, the sensitivity of these varieties are lower and the plant modalities are not influenced bigger; in addition, Nongda 2008, Nongda 108, Xinyu 958 and Taiyu 12 grow healthy, the resistance to nicosulfuron are higher compared with other varieties. There aren’ t clear injury symptoms on these plants. And the sensitive degree of other varieties is between Yudan 2002 and Xinyu 958. Finally, with bioassay method in foster utensil, sensitivity of the maize root length to nicosulfuron is detected: based on IC50, the sensitivity order is: Taiyu 2(zhengjiao)>Jinzhenzhu>Taiyu 7>Zinuo>Taiyu 2(fanjiao)>Taiyu 15>Feiyu 5>Xindan 23>Hudan 2000>Liaoyu 19 >Taiyu 12>Luyuandan 33>Liaoyu 18>Nongda 108>Nongda 2008.