Abstract: This paper reports the observations on the ulstrastructure of microsp-orogenesis and development of Pinus yunnanesis Franch. There were a lot of cell-organelles in sporogenous cells and pollen mother cells. Plasmodesma were obvious within the sporogenous cell walls.Concentric circle-shaped endoplasmic reticula in the pollen mother cells were observed. Starch was surrounded by this kind endoplasmic reticula.The concentric circle-shaped endoplasmic reticula appear variously and distributed singly or concentrically in the pollen mother cells. During this stage, many sharply-defined endoplasmic reticulum demonstrated in a para-llelly arranged bundle-shaped structure in the tapetum cells. At the tetrad stage, pre-Ubisch bodies and sporopollenin grains from tapetum cells secr-eted into microsporangium through plasmalemma and inner tangential wall.Generative cell and tube cell were seperated by a mooned thin wall. There were differences in the position, shape, size and contents of the generative cell and tube cell. These differences decided the different development ways and functions of the generative cell and tube cell in the further dev-elopment of male gametophyte.