In order to have a knowledge of pollen morphology and structure as well as male reproductive characters of Cypripedium japonicum Thunb.,we used SEM(scanning electron microscopy) and TEM (transmission electron microscopy) and fluorescence microscopy to observe pollen ultrastructure and the process of pollen tube growth.The results showed that:(1)Pollen grain presented prolate,smooth surface with a small amount of glue materials and without any characteristics,while some of the surface had two or more deeper depression with spherical protrusions inside.(2)Pollen wall divided into the inner wall with cellulose pectin composition and the outer wall of rod-shaped pillar structure,with covering layer outside.Germ cells were nearly round,of large and dense nucleus;vegetative cells were more curved,with nuclei and cytoplasm dispersion.Pollen cells contained a large number of mitochondria,plastids,vesicles and other organelles,and were rich in starch,protein and polysaccharide.(3)Pollen tubes grew along the direction of elongation of the ovary wall after germination.Twenty days after pollination (DAP),few pollen tubes grew on the ovary wall.A huge number of callose plugs presented in pollen tubes which changed the elongation direction to the middle of ovule 30 DAP.Along with pollen tubes approaching to the ovules,fertilization basically completed 50 DAP.Our study suggested that pollen could develop normally in C.japonicum,which did not hinder the process of generative propagation.