The invention provides an osmunda mildei fertile spore cultivation and reproduction method. The osmunda mildei fertile spore cultivation and reproduction method includes inoculating an MS basic culture medium with sterilized sporangium chips or spore powder, adding 0.5-1.5mg/L of 6-benzyl adenine and 0.01-0.1mg/L of naphthylacetic acid for cultivation, and allowing spores to grow into prothalli gradually from filaments and plates; transferring the prothalli into 1/2MS and 1/4MS culture media for cultivation, and after the volume of the prothalli is obviously increased, transferring the prothalli into the same solid culture medium for cultivation to form spore seedlings; inoculating a culture medium containing 0.5-1.0mg/L of indolebutyric acid with the spore seedlings for cultivation, continuing cultivation in an original bottle for around one month after radicles are formed 20 days later, and transferring the radicles to a pot for cultivation. By the osmunda mildei fertile spore cultivation and reproduction method, the problem of difficulty in reproduction of osmunda mildei is solved, osmunda mildei seedlings can be reproduced quickly in a short time, and rare resources of the osmunda mildei are protected effectively.