The BcMF4 (Brassica campestris Male Fertility 4) gene was previously isolated from the fertile B line of Chinese cabbage-pak-choi (Brassica campestris ssp. chinensis var. communis, syn. B. rapa ssp. chinensis var. communis). In the present paper, based on the cDNA sequence of BcMF4, primers were designed and used to amplify two fragments from the cDNA of flower buds of Chinese cabbage-pak-choi. Two produced fragments were introduced separately into binary vector pBI121 in antisense and sense orientations. The generated RNA interference (RNAi) vector was then mobilized into Agrobacterium tumefaciens strain LBA4404. The A. tumefaciens harboring the BcMF4 fragments was transformed to flowering Chinese cabbage (B. campestris ssp. chinensis var. parachinensis) via tissue culture. Approximately 45.8% of the pollen grains from 72.2% of RNAi plants exhibited abnormal in their shapes, and only 23.7% of the pollen grains from these plants germinated normally. Northern blotting demonstrated that the phenotypic change of pollen grains resulted from the inhibition of expression of the BcMF4 due to the insertion of the transgene. This indicates that functional interrupting of BcMF4 by RNAi resulted in partial pollen abortion in flowering Chinese cabbage, suggesting that the product of BcMF4 gene plays an important role during pollen development of Chinese cabbage such as Chinese cabbage-pak-choi and flowering Chinese cabbage.