Four-month-old babies can roll over, hold things in a more coordinated way, and turn their heads with objects, etc. The details are analyzed as follows: In the fourth month of life, babies can have the ability to turn over on their own, such as lying on their backs and then on their sides, lifting their chests when lying on their backs with two hands, and sitting when holding their hips. At this time, babies can gradually evolve from inaccurate grasping to the ability to separate five fingers accurately, and hand-eye coordination is also better developed. With the development of the baby’s age, the self-control of the head will slowly develop, and can independently turn the head to look around the environment. They can turn their head to look around and can cry or laugh more consciously. The fourth month baby may also have other aspects of the characteristics of parents usually pay more attention to interact with the baby, is conducive to promoting the baby’s brain development.