The formation and development of sporoderm of the fern Pteris vittata L.(Pteridaceae) should be studied using light microscope (LM),scanning electron microscope (SEM) and transmission electron microscope (TEM).The results as follow:The spores are tetrahedral,round obtuse triangle in polar view,semi-circular or super semi-circular in equatorial view.The spores usually have tuberculate ornamentations and proximal ridge in the proximal surface,network ridges in the distal surface and the equatorial flange.The exospore,belonging to the Blechnum type,forms the outline of the spore ornamentations.The solid perispore is composed of two layers.The inner layer is thin and the outer layer is attached with small spherules.Based on the developmental features of the exospore and perispore,it is considered that Pteridaceae has close relationship with Hemionitidaceae and Ceratopteridaceae.The present results support the viewpoint that the Hemionitidaceae and Ceratopteridaceae are contained in the Pteridaceae.