Abstract: Reason of floral sterility of rape under boron deficient condition was explored. Result showed boron deficiency caused the unnormal morphological change of reproductive organ, especially the disorderly tissue structure of fiber layer of anther which induced the difficulty of pollen distribution. The unnormal development of ovary, pollen tube and style makes the obstacle in pollination. In addition, the imbalanced supply of inorganic nutrients and the disorder of biochemical metabolism were also influenced seed formation.