Remains of a kind of plant reproductive organ found in Late Triassic, Jurassic and Tertiary coals in China are reported in this paper. They are similar to megaspores of pteridophyta but have no mono or trilete structures. There are reticulate ornamentations on the surface of the walls. Evidence proves that they are megaspores in seeds of gymnosperms which have been first discovered in coals in China. A preliminary study on the micro- and submicrostructures of walls of the megaspore walls of gymnosperms in coals of various ages has been made using the biomicroscope and scanning electron microscope. The discovery and study of the megaspores of gymnosperms are of important significance in paleobotany, coal petrology and petroleum geology.