Children’s weak legs and frequent falls may be caused by underdeveloped bones, muscle atrophy, potassium or calcium deficiency, and cerebellar hypoplasia. 1. Bones are not well developed: children who are learning to walk often fall down because their bones are not fully developed, the bones are relatively soft, the child’s feet on the ground is also soft, walking too fast, walking for too long will have the phenomenon of falling. 2. Muscle atrophy: muscle atrophy includes neurogenic muscle atrophy, myogenic muscle atrophy, neurogenic muscle atrophy is a neurological lesion leading to a reduction in the use of the corresponding muscle fibers or inability to use, which in turn leads to muscle atrophy. Myogenic muscular atrophy is muscle atrophy caused by diseases of the muscle itself, such as myotonic dystrophy, polymyositis and other diseases, muscle atrophy will have weak legs, walking and often fall down performance. 3. Potassium or calcium deficiency: small children with hypokalemia caused by malnutrition, long-term diarrhea, etc., will have general weakness, legs will feel weak, and often fall down. In the case of calcium deficiency, the development of bones and muscles will be affected, and they may also have weak legs and fall down frequently. 4. Cerebellar hypoplasia: Children with cerebellar hypoplasia may have poor balance and have weak legs and fall down frequently. There are many reasons for children to have weak legs and fall down frequently, and it is recommended to consult a doctor in time for treatment if the condition is serious.