2 and a half year old baby running and falling may be due to imperfect development, calcium deficiency, cerebellar ataxia and other reasons. 1. imperfect development: 2-year-old babies just learn to walk, leg strength is not enough, poor sense of balance, easy to fall when running fast. Generally this is a normal phenomenon, if the situation still occurs as the age grows, then you need to consult a doctor in time. 2. Calcium deficiency: It may be caused by insufficient calcium intake, malabsorption and excessive consumption. The lack of calcium needed to maintain normal physiological functions of the human body may cause a decrease in bone density, muscle spasms, weakness of legs and feet, etc., which can lead to the phenomenon of running and falling. 3. Cerebellar ataxia: It may be due to the occurrence of space-occupying lesions in the brain, hemorrhage and other phenomena, so that the cerebellum is affected. The cerebellum’s ability to balance and coordinate is affected, and the child may suffer from running and falling, drunken gait, intentional tremor and other symptoms. 2.5 year old baby running and falling can also be seen in other reasons, it is recommended to go to the hospital in time, follow the doctor’s instructions for treatment, to avoid delaying the condition.