The blooming of the single flower, the development of microsporangium, male gametophyte, megasporogenesis, female gametophyte and embryogeny of Swertia mileensis, a special herb endemic to Yunnan, were studied in this article. (1) The reproductive growth of S. mileensis begins at late August or early September and the bud stage is last for approximately 35 days, flowering time is last for only 2-3 days while fruit stage is the longest, approximately 40-45 days. (2) There are a series of mechanism to guarantee the cross pollination in S. mileensis, such as the versatile anther; the dichogamy in which the maturity of stamen was about 23 hours earlier than the maturity of pistil, that means the overlapping time of the mature stamen and pistil is only 1-2 hours. Furthermore a new mechanism was observed in which the stamen and pistil would change their position in space to avoid selfpollination. At first anther clings to stamen and then turn around on the back of the pistil after a 180° reversion, while filament deviate lead to the anther bent down with 210°. Section shows: anthers are tetrasporangiate. The development of anther walls conforms to the basic type and comprises of epidermis, endothecium, two middle layers and tapetum at the mature stage. The tapetum cells have dual origin and belong to the glandular type. The anther locules have degenerating tapetum nuclei in the middle which are from the early dividing and intruding of the tapetum. Two middle layers are ephemeral; endothecium reduces and epidermis persists and develops to become fibrousthickening. The cytokinesis of the microspore mother cell in meiosis is of the simultaneous type. Most of the microspore tetrads are tetrahedral and pollen grains are 2celled and 3celled when shed. The ovary is bicarpellate, unilocular with some series of ovules located at the parietal placentation. The ovule is unitegmic, enuinucellar and anatropous. The one chalazal megaspore in linear tetrad becomes the functional megaspore and the development of female gametophyte is the polygonum type. Three antipodal cells have multiseriate nuclei and distinct haustorium, and persist like a layer of “outer endosperm” just out of the endosperm nucleus layer. Fertilization is porogamous and of premitotic syngamy type. The development of endosperm conforms to nuclear type and the embryogeny corresponds to the solanum type. The embryo is at the late early heartshaped stage when seeds released from the capsule. The developed antipodal cells and suspensor structure has magnificent significance for the reproductive adaptation and evolution of the seed afterripening of S. mileensis.