The study analyzed the silencing of BcMF12 gene regulated by BcA9 promoter in the transgenic pakchoi and confirmed the effect of antisense BcMF12 gene on the pollen development.A conserved BcMF12 gene fragment was amplified from the cDNA of flower buds in pakchoi(Brassica campestris L.ssp.chinensis,syn.B.rapa L.ssp.chinensis)and was fused to the anther specific BcA9 promoter.The plant antisense expression vector was constructed and then introduced into pakchoi via Agrobacterium-mediated transformation.The transgenic plants were screened by antibiotics and molecular analysis.PCR and Southern blot revealed that the antisense BcMF12-GUS fusion gene regulated by BcA9 promoter was integrated into transgenic plants.Northern blot suggested that the expression of BcMF12 gene was down-regulated significantly.The pollen germination rate of transgenic plants with antisense BcMF12 gene decreased as compared with that of the control plants.The expression of the gene BcMF12 related to the pollen development was inhibited by the antisense BcMF12 driven by BcA9 promoter,which consequently affected the pollen development in pakchoi. The study analyzed the silencing of BcMF12 gene by BcA9 promoter in the transgenic pakchoi and confirmed the effect of antisense BcMF12 gene on the pollen development. A conserved BcMF12 gene fragment was amplified from the cDNA of flower buds in pakchoi (Brassica campestris L.ssp . chinensis, syn. B. rapa L. sp. chinensis) and was fused to the anther specific BcA9 promoter. The plant antisense expression vector was constructed and then introduced into pakchoi via Agrobacterium -mediated transformation. The transgenic plants were screened by antibiotics and molecular analysis. PCR and Southern blot revealed that the antisense BcMF12-GUS fusion gene regulated by BcA9 promoter was integrated into transgenic plants. Northern blot suggested that the expression of BcMF12 gene was down-regulated significantly. The pollen germination rate of transgenic plants with antisense BcMF12 gene decreased as compared with that of that of the control plants. The expression of the gene BcMF12 related to the pollen dev elopment was inhibited by the antisense BcMF12 driven by BcA9 promoter, which results affected the pollen development in pakchoi.