In modern society, children’s psychological problems are receiving more and more attention, yet many young parents are often puzzled and do not know what to do when faced with abnormal behavior in their children. Today, we share the common problems of children under 6 years old and remind parents that they need to go for professional consultation to understand the situation if necessary. 1, nail biting Nail biting is a very common maladaptive behavior in childhood, which can occur in both boys and girls. The degree of severity varies, and in severe cases can cause local bleeding and even nail infections. Children who love to bite their nails are often accompanied by sleep disturbances and twitching. 2, finger sucking Finger sucking is a common phenomenon in infancy, and after 2-3 years of age, this phenomenon will be significantly reduced. It will gradually disappear as the child gets older. If it does not disappear, it is a bad behavioral deviation. 3. Stuttering is a state of interrupted, repetitive, and non-fluent speech, and is a common language disorder in childhood. About half of the children who stutter develop it before the age of 5. 4. Delayed speech development refers to the delayed emergence and slower development of oral language in children compared to normal children of the same age. It is generally considered that children who cannot speak words at 18 months and those who cannot speak phrases at 30 months have delayed speech development. 5. Selective mutism refers to children who have acquired the ability to speak, but remain silent in certain situations because of psychiatric factors. For example, they do not speak at school, but speak at home. This psychological problem mostly starts at the age of 3-5 years. 6. Enuresis refers to children over 5 years old who cannot control their own urination and often wet their beds at night and sometimes wet their pants during the day. It is mostly seen in children aged 5-10 years old, more in boys than in girls. 7, tic disorder Refers to a group of muscles or two groups of muscles confined to a certain part of the body appearing twitching. It is characterized by blinking, eyebrow squeezing, forehead wrinkling, lip smacking, neck stretching, head shaking, lip biting and imitation of strange equations, mostly seen in children over 5 years old, more boys than girls. Night terrors are sudden awakening during sleep, staring and sitting up, panic, painful expression, often accompanied by crying, shortness of breath, sweating and other symptoms, mostly occurring within 2 hours after going to sleep, and cannot be recalled after waking up. It is most common in children aged 5-7 years old. 9. Aggressive behavior refers to behavior that is harmful to others and destroys objects because the desire is not satisfied. Children’s aggressive behavior is often manifested as hitting, cursing, pushing, kicking, grabbing others’ things (or toys), etc. The first peak of aggression in children generally occurs at the age of 3-6 years, and the second peak occurs at the age of 10-11 years. Overall, aggression can be divided into two categories: violent aggression and verbal aggression, with violent aggression predominating in boys and verbal aggression in girls. 10. Withdrawal behavior is the undesirable behavior of timid, shy, lonely, afraid to go to unfamiliar environments and unwilling to play with children. Such children are not interested in new things and lack curiosity. 11, neurogenic frequency Refers to a psychological disorder in which the number of urination per day increases significantly, but the volume of urination does not increase and the urine routine is normal. The number of urination can increase from the normal 6-8 times to 20-30 times, or even more than a dozen times per hour, with very little urination each time, sometimes only a few drops. It is more common in children aged 4-5 years old. 12.Autism is a group of disorders characterized by severe loneliness, lack of emotional response, language development disorder, stereotyped repetitive movements and peculiar reactions to the environment, mostly seen in boys.