Familial non-autoimmune hyperthyroidism is a rare autosomal dominant genetic disease resulting from activating mutations in the thyroid-stimulating hormone receptor (TSHR) gene. In this work a Chinese family with autosomal dominant non-autoimmune hyperthyroidism across four generations was collected. The strongest evidence for linkage in this study occurred on chromosome 14q24.2–31.3. By mutation scan of the TSHR gene located within the region of interest, a heterozygote substitution (A > T) at position 2071 of the TSHR was found, changing isoleucine 691 to phenylalanine. Our study identified the first germline mutation in the intracellular C-terminal domain of TSHR.