Bad oral habits refer to the repeated repetition of the same action, consciously or unconsciously, for a certain interval of time and persistently. Bad oral habits in children are one of the main causes of malocclusion, so parents need to pay attention to whether their children have such bad habits, and if they do, they need to break them early. Bad oral habits include finger-sucking habits, tongue habits, lip habits, lateral chewing habits, biting habits and sleeping habits, etc. 1, finger sucking habits: In general, finger sucking habits before the age of 2 or 3 years old can be regarded as a normal physiological activity, this habit will usually gradually reduce in 4 to 6 years old and disappear on its own. If the finger sucking habit continues to exist after this time and has a certain intensity, it can lead to obvious malocclusion. Long-term finger-sucking habits of children are often seen on the fingers with calluses, fingers will also have bending and other phenomena, which is an important sign for parents to determine whether the child has a finger-sucking habit. 2, tongue habits: children often use the tip of the tongue to lick the loose milk teeth, milk tooth stumps or the first eruption of permanent teeth when changing teeth, if the action only exists in a relatively short period of time, it will not cause obvious malocclusion. However, if this action persists for a long time, forming a habit of licking teeth, spitting out the tongue or extending the tongue, it can lead to obvious malocclusion. Parents also need to pay attention to whether the child suffers from chronic tonsillitis, chronic laryngitis and other diseases, because such diseases can affect the child’s respiratory tract, the child often tongue out to the front, therefore triggering bad tongue sticking habits. 3, lip habit: at first, children may appear because of emotional reasons and lip biting action, but if long-term presence can form lip biting habit. Biting the lower lip habit will lead to lip tilting and protrusion of the maxillary front teeth, and the appearance of the maxillary teeth gap; while the mandibular arch and mandibular bone forward development is hindered, forming the mandibular front teeth area of crowding, deep overlap of the front teeth, jaw retraction, open lips and teeth and other deformities. The habit of biting the upper lip will form the anterior teeth anticlinal (Diastasis), the lingual inclination of the maxillary anterior teeth, mandibular protrusion and proximity misalignment and other deformities. 4, lateral chewing habit: due to one side of the back teeth area has serious tooth decay, or multiple missing teeth and other problems, the side of the back teeth can not exercise the normal or due chewing function, only by the healthy side of the teeth to assume all the chewing function, and over time formed a lateral chewing habit. The presence of long-term lateral chewing habits can cause facial asymmetry (small and large face). 5. Biting habits: Most often seen chewing on pencils or nails. Some children in infancy and early childhood developed some habits such as chewing on corners of clothes, cuffs, handkerchiefs, corners and sucking rubber nipples, etc. In essence, these habits, like finger-sucking habits, are normal physiological reflexes of a specific growth and development period, and their short-term existence does not have serious effects. Generally, after leaving infancy, these habits will disappear naturally as the brain develops and the neuromuscular system matures. However, if these habits still exist for a long time, it will become a bad habit that affects the growth and development of the oral and maxillofacial area, leading to the occurrence of localized open and closed deformities. 6, sleep habits: when children sleep, they often use their hands, elbows or fists to pillow under one side of the face, and sometimes use their hands to hold one side of the cheek to read or think about problems, this bad posture can become a bad habit if it continues and happens for a long time, hindering the normal growth and development of the teeth and jaws and may lead to asymmetry of the facial structure. Therefore, if parents find that their children have such bad oral habits, they must take early measures to guide their children to break the bad habits, and if the results are not obvious, they can seek the help of orthodontists.