In this test, the flowering temperature, the vigor of stigma and pollen, the reason of self-hybrid degeneration in radishes was studied. The results showed that: structure of flower organ of malt sterile line in radish is different from its maintainers and normal plant (self-hybrid plant). Anther’s development has three types: they are yellow degenerative corolla, abortive pollen, and half-abortive pollen. The flowering period of winter radish is 30－45 days. Flowering amounts a day is significantly positively related with temperature. Seed setting rate is the highest when the stigma that of the day before flowering hybridized with the flowering anther, the flowering of spring summer radish is influenced by many factors such as temperature and sunlight. When the temperature is high it can flower partly, but anther growth is not normal, the flowering period is short, and seed setting rate is low. Self-hybrid degeneration of radish is concerned with declining of the pollen.