Objective　To explore the clinical features and mutations of thyroid hormone receptor beta gene of resistance to thyroid hormone syndrome. Method　The clinical data of a child with resistance to thyroid hormone syndrome was retrospectively analyzed, blood samples were analyzed for related genes using targeted exome capture with high throughput sequencing. Detected variants were confirmed by Sanger sequencing. Results　The proband was a 12-year-old boy, clinically manifested with growth retardation, occasional palpitation, no enlargement of thyroid gland. Laboratory tests showed increased free triiodothyronic acid and free thyroxine levels and normal thyroid stimulating hormone level. Targeted sequencing identified a novel heterozygous pathogenic variant in THRB in proband and his father that resulted in the 835 base changed from guanine to adenine, thus causing the substitution of alanine to threonine at position 279 of the protein. His mother had two normal alleles at this locus. Conclusion　Gene detection is helpful for the diagnosis of RTH beta.