There are many reasons, among which two reasons are common. One is the bad habit, the other is eye discomfort caused by eye diseases. When babies cry, play or feel uncomfortable in the eyes, they are usually fond of rubbing their eyes, then the bad habit is formed. Under such circumstance, you should help your baby wash and dry the sweat or dustiness on his/her face or around his/her eye in time in order to reduce the chance of rubbing the eyes. With the material life enriching and the living condition improving, the eye diseases of allergy among children are increasing, in this situation, you should take your baby to see a doctor and at the same time find out whether there are obvious anaphylactic sources, such as the newly-decorated living room, seafood, flowers, etc.