Abstract: The aim of this study was to analyze the morphological characteristics and cytological characteristics of anther development in two male sterile lines of cauliflower (Brassica oleracea var. botrytis). The cauliflower cytoplasmic male sterile line 09-R9, the maintainer line 09-24, and the temperature-sensitive genetic male sterile line GS-19 were used as the test materials, and morphological and cytological techniques were used to study anther development. There were differences between the two male sterile lines in fertility transition, flower morphology, and anther development. The three lines showed variations in fertility under different temperature treatments. The sterility of 09-R9 and 09-24 was not affected by temperature; 09-R9 was always sterile, and 09-24 was completely fertile. GS-19 was affected by temperature, and was sterile at high temperature (20 ℃) but fertile at a lower temperature (15 ℃). The buds and anthers were smaller in GS-19 than in 09-R9. Sterile plants differed from fertile plants, and there were significantly fewer flowers on sterile plants than on fertile plants. Microstructural observations showed that the anthers abortive stages and types differed between the two male sterile lines. 09-R9 formed a normal-shaped pollen sac at the early anther stage, but the materials within pollen sacs gradually disintegrated as buds developed, and the pollen sacs finally disappeared. The development of anthers was blocked before the formation of the pollen mother cell, so this line showed an abortive-type sterility without pollen sacs. The anther development of GS-19 showed differentiation of the pollen mother cell and normal pollen sac formation, but this line produced very small amounts of non-viable pollen and no viable pollen. In this line, the pollen mother cells did not undergo meiosis to form tetrads, but formed pseudo microspores with abnormal pollen exines. As the anthers developed, the pseudo microspores gradually decayed until only the empty shells remained. The anther development of GS-19 was blocked between the pollen mother cell stage and the tetrad stage, and so it was an abortive-type sterility of the pollen mother cell. These ultrastructural observations revealed the similarities and differences in anther abortion between the male sterile lines 09-R9 and GS-19 under high-temperature conditions.