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Recombinases are in part responsible for homologous recombination and genome integrity during DNA repair. <i>DMC1</i> has a typical RecA domain, and belongs to the recombinase superfamily. The reactive oxygen species (ROS) as a potent DNA damage agent is produced during seed germination under stress conditions. DNA repair should be initiated immediately to allow for subsequent seedling development. In this study, we attempted to characterize the underlying mechanism of <i>BrDMC1</i> responsiveness to salinity stress using the RNA interference approach in <i>Brassica rapa</i> (<i>B. rapa</i>). Bioinformatics and expression pattern analysis revealed that <i>BrDMC1</i> only retained <i>BrDMC1</i>.A01 after the whole genome triplication (WGT) event and was primarily transcribed in flowers and seeds. <i>BrDMC1</i> had high activity in the promoter region during germination, according to histochemical GUS staining. The data showed that salt treatment reduced the germination rate, weakened seed vigor and decreased antioxidant enzyme activity, but increased oxidative damage in <i>BrDMC1</i>-RNAi seeds. Furthermore, the expression of stress-responsive genes and damage repair genes was significantly different in transgenic lines exposed to salt stress. Therefore, <i>BrDMC1</i> may respond to salt stress by controlling seed germination and the expression of stress-related and damage repair genes in <i>B. rapa</i>.