The main clinical manifestations of Down’s syndrome, also known as congenital stupidity, are: 1) intelligent backwardness; 2) special facial features, such as dull expression, small eye fissures, wide eye spacing, upward sloping canthus of both eyes, low nasal bridge, small external ears, open mouth and tongue, salivation, small and round head, short and wide neck; 3) growth retardation, short body, short limbs, late teething and abnormal sequence, ligament laxity, low muscle tone, short and thick fingers, especially short little finger; 4) skin characteristics, may have through hands; 5) accompanied by a variety of malformations, 50% have congenital heart disease, followed by digestive tract malformations, immune deficiency, etc.