To explore the effects of multi-walled carbon nanotubes in gametophyte development and sporophyte production of Ceratopteris thalictroides， and to lay a foundation for conservation and breeding of endangered ferns.C. thalictroides was used as material， and five treatment group of 0（the control）， 0.5， 1.0， 2.5， 5.0 mg·L^-1 was set，and the effects of different mass concentrations of multi-walled carbon nanotubes on gametophyte development and sporophyte formation of C. thalictroides were observed by light microscope. The results showed that compared with the control group， 0.5-2.5 mg·L^-1 multi-walled carbon nanotube treatment could advance spore germination by about 15 d， among them， 0.5 mg·L^-1 multi-walled carbon nanotubes had the best effect on spore germination， 0.5-1.5 mg·L^-1 multi-walled carbon nanotubes had the best effect on protonema and plate formation， and 2.5 mg·L^-1 multi-walled carbon nanotubes had the best effect on prothallus and sporophyte formation. High mass concentration （5.0 mg·L^-1） of multi-walled carbon nanotubes led to deformity of some gametophytes， and spermogonium degradation， chlorosis of chloroplasts in cells， and chlorosis of chloroplasts in some cells on the developing sporophytes cells. In addition， male gametophytes was promoted by the addition of multi-walled carbon nanotube. In conclusion，0.5-2.5 mg·L^-1 multi-walled carbon nanotube treatment might significantly promote gametophyte development and sporophyte production of C. thalictroides， and the number of spermogonium increased significantly， and both monoecious and dioecious gametophytes appeared simultaneously， high mass concentration of multi-walled carbon nanotube treatment might result in‘high concentration inhibition’ of gametophyte development of C. thalictroides. In the process of practical application， the corresponding addition amount should be selected based on the specific need.