Abstract:A series of researches were studied on megasporogenesis, microsporogenesis and the development of male and female gametophytes in fertile line and male sterile line’s flowers of Tagetes erecta L. by the paraffin sectioning method. The cytological observation showed that the ovaries of both fertile line and male sterile line had one chamber, each of which had one ovule that was unitegmic, tenuinucellate and anatropous. After meiosis, the megasporocytes divided into four linearly arrayed megaspores, the ones of which at chalazal end usually had functional capacity. The development of embryo sacs belonged to polygonum type. The microsporic tetrads of the fertile line belonged to the tetrahedral type, and mature pollen was two-celled with bristles on the surface. The anthers of the fertile line had four microsporangiates, and the development of anther wall was of dicotyledonous type and the tapetum belonged to glandular type. The anther’s development of male sterile line was blocked at the stage of flower bud differentiation. There was not the primordium of stamen in male sterile line’s mutative floret during the differentiation.