Abstract: The control efficiency of fluroxypyr · mesotrione · nicosulfuron 50% WDG on grassy weeds, broadleaf weeds and sedge, and its herbicide controlling spectrum and safety were studied by field experiments, and the optimal dosage and medication time were explored. The results showed that under stem spraying at the stage of corn 3—5 leaves and weed 3—6 leaves with the dosage of 240-600 g/hm2, fluroxypyr· mesotrione·nicosulfuron 50% WDG had better control efficiency on grassy weeds, broadleaf weeds and sedge, the control efficiency after 15 d reached 66.1%-85.7% the control efficiency after 30 d reached 88.8%-100% and the control efficiency after 45 d reached 90.88%-100%, and the control efficiency increased with the dosage. There was no phytotoxicity occurred during the whole growth period after application, which indicated that the agent was safe to spring maize, and it also had no impact on other non-target organisms. The best dosage was 300-320 g/hm2.