miRNAs participate in the regulation of apoptosis. However, it remains largely unknown as to how miRNAs are integrated into the apoptotic program. Mitochondrial fission is involved in the initiation of apoptosis. It is not yet clear whether miRNAs are able to regulate mitochondrial fission. Here we report that miR-30 family members are able to regulate apoptosis by targeting the mitochondrial fission machinery. Our data show that miR-30 family members can inhibit mitochondrial fission and the consequent apoptosis. In exploring the underlying molecular mechanism, we identified that miR-30 family members can suppress p53 expression. In response to the apoptotic stimulation, the expression levels of miR-30 family members were reduced, whereas p53 was upregulated. p53 transcriptionally activated the mitochondrial fission protein, dynamin-related protein-1 (Drp1). The latter conveyed the apoptotic signal of p53 by initiating the mitochondrial fission program. miR-30 family members inhibited mitochondrial fission through suppressing the expression of p53 and its downstream target Drp1. Our data reveal a novel model in which a miRNA can regulate apoptosis through targeting the mitochondrial fission machinery.