Mutations in mitochondrial DNA, especially in mitochondrial tRNA (mt-tRNA) genes, are the important causes for maternally inherited hypertension. In this study, we reported the clinical, genetic, and molecular characterization of a Han Chinese family with hypertension. Most strikingly, this family exhibited a high penetrance and expressivity of hypertension. Sequence analysis of the complete mt-tRNA genes showed the presence of tRNA(Met) A4435G and tRNA(Ala) C5601T mutations. The A4435G had already been reported as a pathogenic mutation associated with hypertension; in addition, the C5601T mutation, which was located at the highly conserved nucleotide of T arm of tRNA(Ala), created a novel Watson-Crick base pairing and may result in failure of tRNA metabolism. Moreover, bioinformatics analysis indicated that the C5601T mutation altered the secondary structure of tRNA(Ala). Thus, the mitochondrial dysfunction, caused by the A4435G mutation, may be worsened by the C5601T mutation. Taken together, our data indicated that the co-occurrence of the A4435G and C5601T mutations may account for the high penetrance and expressivity of hypertension in this family. Therefore, our study provided novel insight into the pathophysiology of maternally inherited hypertension.