Abstract: The environmental impacts of herbicides cannot be overlooked when increasing attention is being focused on environmental issues.It is possible that rice herbicides are having adverse effects on ontarget plants that grow around paddy fields.The effects of herbicide quinclorac on sexual reproduction of Ceratopteris pteridoides the second category of the key protected wild plants were studied in this paper.Results showed that quinclorac had no effect on germination of C.pteridoides.However,it dose-dependently inhibited the gametophyte growth of C.pteridoides with the EC₅₀ of 0.48 mg·L^-1.The hermaphrodite gametophyte ratio was reduced and archegonium differentiation was delayed with dose dependent manner when quinclorac concentrations were higher than 0.1 mg·L^-1.While quinclorac concentration reached 4 mg·L^-1,male but no hermaphrodite gametophyte formed.These results indicate that quinclorac affects the sexual reproduction of C.pteridoides by inhibiting the gametophyte growth and indirectly disturbing the antheridiogen systems of C.pteridoides.This can provide fundamental data to the ecological risk assessment of herbicides contamination on nontarget aquatic plants and protect the aquatic plant biodiversity.