Objective　To explore the characteristics of TG gene mutation in a family with congenital hypothyroidism (CH) and low thyroglobulin (TG) and further to analyze the relationship between genotype and clinical phenotype. Method　The genomic DNA was extracted for TG gene detection from peripheral blood of two siblings in a CH family with low TG. Results Two heterozygous variations, c.274+2T>G and c.2512C>T, were found in TG gene of their father and mother, respectively. Both of the two mutations above were found in the TG gene of two siblings and are compound heterozygous mutations. The c.2512C>T was a newly discovered mutation site, and the pathogenicity has not been reported in the literature. Conclusion　Mutations in the TG gene cause changes in protein function leading to CH. The study found a new TG gene mutation site.