The study was conducted in order to explore the microsporogenesis process and the abortive cytologic characters of the male sterile line PA.With male sterile line PA and maintenance line PB of Platycodon grandiflorum as materials,we observed the mitosis process of pollen mother cells and the development of the male gametophytes by the methods of conventional paraffin slicer and squashing technique staining with the solution of improved phenol fuchsin.The results show that:(1)The pollen mother cells carried on their meiosis and cytokinesis simultaneously.Chromosomes segregations of pollen mother cells in same anther were synchronous step during meiosis.Their tetrads were tetrahedral types.At metaphases Ⅰ and Ⅱ,there showed a small number of chromosomes scattered outside their equatorial plate.Mature pollens were ones with two-cells.(2)The abnormal meiosis of pollen mother cell from male sterile line was observed at anaphase Ⅰ,namely,cytoplasmic morpha appear abnormality.Cytoplasm could not segregate and formed heteromorphous tetrad after telophaseⅡ.Microspores were not released from tetrads due to not degradate from callose wall.Those are important reasons of abortion of the microspore from sterile line.(3)The contents of free proline,and soluble protein in flower buds at different development stages of male sterile line were lower than those of viable line.The activity of SOD and the content of malondialdehyde (MDA) in male sterile buds were higher than those of viable buds at all time.(4)There were significant differences in mother cells meiosis and the male gametophytes development of male sterile and maintenance lines.Abortive microspores approximately included four phases:abortive cytoplasm was present at anaphase Ⅰ,cytoplasm was not separated after telophase Ⅱ,microspores were not released from tetrad,and then tetrads were digested.High activity of reactive oxygen species scavenger enzymes,high content of MDA and low content of free proline may be the results on male sterility of P.grandiflorum.