The manifestations of brain injury in preterm infants include the state of consciousness, muscle tone, abnormal reflexes, the presence of convulsions, pupil condition and other manifestations. 1. Abnormal state of consciousness: after brain injury of preterm infants, irritability, drowsiness, coma and so on may appear. 2. Abnormal muscle tone: if the symptoms of injury are mild, the muscle tone may not be abnormal, while the symptoms may be severe and the muscle tone may be reduced or increased. 3. Abnormal reflexes: a variety of normal reflexes disappear, such as the embrace reflex, which may be weakened or even disappear. Sucking reflex, mild symptoms may be normal sucking, severe may appear weakened. 4. Convulsions, mild injuries may have myoclonus, moderate with convulsions, or even a persistent state. 5. Pupil situation, mild brain injury, pupil dilation, so the symptoms of aggravation may be narrowed, or even the two sides of the unequal size, light reflex retardation. The manifestations of brain injury in premature infants are complex and require professional evaluation by a doctor.