Abstract: The research on determining the influence of the herbicide safener 3-dichloroacetyl-2-meth yl-2-ethyl-1,3-oxazolidine on corn by a room bioassay. Under a definitely herbicide Chlorsulfuron concentrations, herbicide safener concentrations correlated with the root length and the fresh weight of roots of corn. The safener has a definitely biological activity, and could protect corn from herbicide Chlorsulfuron of different concentrations injury. The protected rates of the safener to corn from Chlorsulfuron injury were 60%~170%.