Objective　To explore the clinical and genetic characteristics of Rubinstein-Taybi syndrome (RSTS). Method The clinical data of a RSTS child diagnosed by gene test was retrospectively analyzed. Results　A male infant, more than 5 months old, had special face such as thick eyebrows, protruded supercilliary arch, down slanting palpebral fissures, epicanthus and ptosis. The whole exome sequencing revealed that there was a missense mutation of c.3609G > C (p.K1203N) in CREBBP gene. Sanger sequencing did not find that his parents carried the above mutations. It may be a new mutation. Conclusion　The mutation site of c.3609G > C (p.K1203N) in CREBBP gene was found and it enriched the gene mutation spectrum of RSTS.