Abstract:Abstract This paper a preliminary account on the phytogeographical affinities of Pteridophytes between China and Japan. They are generalized as follows: The Fern--flora between China and Japan is closely related. There are 7 common endemic genera e. g. Ptilopteris, Drymotaenium, Saxiglossum, Chi- eniopteris, Leptorumhra, Cyrtomidictyum, Leptomicrosorium and 461 spe- cies in two countries which occupy 74.5% of the total specics of Japan. A demons-trative composition of Fern-flora from the two countries, perhaps, the majoritis of ferns are Dryopteridaceae and Athyriaceae. It shows that the Fern-flora in two countrics was formed before the Japaese Island separated from the Chinense continent in the end of Tertiary. The Sino-Japan Fern-flora has the same origin and is being parallely developed up to now. Some species of ferns which widely distributed in Japan are scattcrly distributed along the coast of China (or vice versa). We consider that thcse species may be newly added in the last regin.