The process of baby’s intellectual development is not always smooth and requires careful and sensitive care from the mother and father. Especially for smaller babies, once the problem appears, if it can be detected early and treated as early as possible, it can clear the obstacle on the baby’s intelligent development and prevent it from happening. 1, the newborn period, if the baby’s head circumference looks significantly smaller, to consider whether there is a small head deformity. When a normal newborn is born, the head circumference of a male baby is 31.8-36.3 cm, and that of a female baby is 30.9-36.1 cm; at full term, the head circumference of a male baby is 35.4-40.2 cm, and that of a female baby is 34.7-39.5 cm. 2. After birth, the baby sleeps all day, rarely cries and makes noise, does not give trouble to others, has little reaction to the surroundings, lacks interest, and has poor attention and reaction at the same time. Although such a baby will be mistaken by parents as very well-behaved, it is actually one of the manifestations of psychological behavior disorder. 3.At 3 months of age, the baby’s neck is still weak and cannot lift its head by itself, and there are other signs of backward motor development; it does not pay attention to what others say, and is often mistaken for deaf due to lack of reaction and insensitivity to sound; its eyes do not gaze around, and is often mistaken for blindness; it does not smile when it sees its relatives, and has little reaction. 4.Normal babies often like to gaze at their hands and play with them repeatedly when they are about 3 months old. If the baby is still persisting in this action after 6 months, it may be an abnormal situation. 5.At 6 months of age, baby’s neck is still weak, his eyes always look at his hands and do not respond to people and things around him, he lacks interest in his relatives, he does not chew when he eats and often has difficulty swallowing, he always lies down honestly every day, sleeps all day, never cries, and has no request to eat or play. 6.By 9 months, baby still can’t roll over, can’t sit and crawl, can’t grab the toys around, can’t turn the toys over, can’t pinch small things with thumb and forefinger, can’t make ba-ba, ma-ma syllables, always lying down every day, still can’t refuse the action, also have no request to eat and play, then we should consider the intelligence problem. 7. At the age of 1 year, the baby still can’t crawl and sit, can’t extend the index finger, can’t use the index finger to point to people and things, and can’t do the action of picking and digging, often shows aimless hyperactivity, can’t concentrate, and is easily irritated. 8. In the 6-12 months stage, normal babies always like to put things in their mouths, but as they develop, they no longer do so, while in babies with intellectual problems, this behavior will persist until after 2 years old. 9.After the baby is one year old, in addition to not sitting and crawling, the baby can’t stand, and has sluggish eyes, flabby body, poor life skills, and often drools, while the normal baby will not drool at this age. 10.When walking, babies often fall down because their feet collide with each other, but this phenomenon will not happen again after normal babies can walk. 11. The baby learns to chew food very late, so it is difficult to feed, and often has difficulty swallowing because it cannot chew solid food, which leads to frequent vomiting when eating. 12. Normal babies stop intentionally throwing things to the ground by the age of 1 year, 3 months to 4 months, while abnormal babies will continue this behavior for a long time. 13. Does not respond to stimuli, such as repeated and continuous stimulation to cause crying. The cry is either a scream or a straight sound, unlike the normal child’s cry, which has a change in pitch.