[Objective]The paper was to study efficacy and phytotoxicity of different dosages of 4% nicosulfuron on weeds in corn fields.[Method]With summer corn variety Zhengdan 958commonly used in field production in Hengshui area of Hebei Province of China as the test material,different dosages(1 050,1 500 and 1 950mL/hm2)of corn postemergence herbicide 4% nicosulfuron SC were sprayed during five-leaf stage of corn,and the treatments with water spraying and manual weeding were set as controls.The effects of different dosages of 4% nicosulfuron SC on weed control efficacy and safety and yield of corn were analyzed in order to determine the optimal dosage.[Result]Spraying 4% nicosulfuron SC with dosage of 1 500mL/hm2 during five-leaf stage of corn not only had better control effect against various weeds,but also did not produce phytotoxicity on corn,and the yield of corn was higher.[Conclusion]The study provided scientific information for using 4% nicosulfuron to eradicate weeds in corn fields. [Objective] The paper was to study efficacy and phytotoxicity of different dosages of 4% nicosulfuron on weeds in corn fields. [Method] With summer corn variety Zhengdan 958commonly used in field production in Hengshui area of ​​Hebei Province of China as the test material, different dosages (1 050,1 500 and 1 950 mL / hm2) of corn postemergence herbicide 4% nicosulfuron SC were sprayed during five-leaf stage of corn, and the treatments with water spraying and manual weeding were set as controls. the effects of different dosages of 4% nicosulfuron SC on weed control efficacy and safety and yield of corn were analyzed in order to determine the optimal dosage. [Result] Spraying 4% nicosulfuron SC with dosage of 1 500mL / hm2 during five-leaf stage of corn not only had better control effect against various weeds, but also did not produce phytotoxicity on corn, and the yield of corn was higher. [Conclusion] The study provided scientific information for using 4% nicosulfuron to eradicate weeds in corn fields.