The special appearance of Down’s syndrome patients includes wide eye spacing, upward slanting of the outer corners of the eyes, inner canthus, low ear position, low nasal bridge, wide and thick tongue, often half-open mouth or tongue sticking out of the mouth, deep and many tongue clefts, thick palms with short and thick fingers, short and small last fingers often bent inward or with two knuckles, and 40% of children with through palms. In the metatarsal pattern, the tibial arch of the ball area of the thumb, the distance between the thumb and the second toe finger is large, and the joint ligaments are lax or see low muscle tone. The diagnosis of Down syndrome is based on: (1) Mental retardation: Mild to moderate, mostly moderate mental retardation, with a gradual decrease in intelligence with age. (2) Language development disorder: The average age of children who start to learn to speak is 4-6 years old. 95% of them have articulation defects, slurred speech, stuttering and low voice; more than 1/3 of them have abnormal speech rhythm or even outburst sounds. (3) Behavioral disorders: Most of the patients are mild-mannered, often giggle, like to imitate and repeat some simple actions, and can perform simple labor. A few patients are irritable, capricious, hyperactive, and even have destructive and aggressive behaviors, and some show a tendency to flinch, accompanied by posture of catatonia. (4) Delayed motor development: The motor function of the child may not differ much from that of a normal child of the same age during the period after birth, but the difference increases with age. Motor development also varies widely among patients. Patients with congenital dysmorphia can perform simple movements such as dressing and eating, but their movements are clumsy, uncoordinated, and their gait is unstable. (5) Growth disorders: Maternal gestation period is shorter in patients with congenital dwarfism, averaging 262 to 272 days. At birth, the height is l~3 cm shorter than normal newborns, the head circumference is basically normal, the biparietal diameter is within the normal range, the anterior-posterior diameter is relatively short, and the occipital area is flat. Most of them have a short head shape. The fontanelle and forehead sutures are wide and close late, and the third fontanelle (the sagittal suture above the posterior fontanelle is widened) often appears. Most children with this disease sleep deeply for a few days after birth, sucking and swallowing are very slow, or even completely unable, so it is very difficult to wake up and feed. 80% of children with this disease have generally low muscle tone. (6) Special appearance: wide eye spacing, upward slanting of the outer corners of the eyes, inner canthus, low ear position, low nasal bridge, wide and thick tongue, mouth often half open or tongue sticking out of the mouth, deep and many furrows on the tongue, thick palm and short thick fingers, short last finger often bent inward or two knuckles, 40% of children with through palm. In the metatarsal pattern, the tibial arch pattern in the ball area of the thumb, the distance between the thumb and the second toe finger is large, and the joint ligaments are lax or see low muscle tone. (7) About 1/2 of the cases are complicated by congenital heart disease: susceptible to infectious diseases and leukemia.