MADS-box is a vital transcription factor family that functions in plant growth and development. Apart fromAPETALA2, all genes in the ABCDE model that explain the molecular mechanism of floral organ development belong to the MADS-box family. Carpel and ovule numbers in plants are essential agronomic traits that determine seed yield, and multilocular siliques have great potential for the development of high-yield varieties ofBrassica. In this study, ABCDE genes in the MADS-box family fromBrassica rapawere identified and characterized. Their tissue-specific expression patterns in floral organs and their differential expression in different pistil types ofB.rapawere revealed by qRT-PCR. A total of 26 ABCDE genes were found to belong to the MADS-box family. Our proposed ABCDE model ofB.rapais consistent with that ofArabidopsis thaliana, indicating that ABCDE genes are functionally conserved. These results of qRT-PCR showed that the expression levels of class C and D genes were significantly different between the wild-type (wt) and tetracarpel (tetrac) mutant ofB.rapa. Interestingly, the expression of the homologs of class E genes was imbalanced. Therefore, it is speculated that class C, D, and E genes are involved in developing the carpel and ovule ofB.rapa. Our findings reveal the potential for the selection of candidate genes to improve yield traits inBrassicacrops.