Abstract:The spores of Alsophila spinulosa (Wall. ex Hook.) R. M. Tryon, A. costularis Baker and Sphaeropteris brunoniana (Hook.)R. M. Tryon were cultivated in soil medium. The gametophyte development of the three species were observed under light microscope in spore germination, filament development, the formation and differentiation of prothallial plate and apical point, the rhizoid feature, and the development and differentiation of the antheridium and archegonium. We also reported ultrastructure of prothallus infected by fungi. The systematic significance of their gametophyte development in Cyatheaceae is discussed, as well as the causes of sexual generation endangerment.