A seven-month-old baby who still can’t sit down may be normal, or it may be caused by conditions such as white matter damage in the brain of premature babies and congenital brain development abnormalities. Generally healthy and full-term babies have a certain pattern of brain motor development, following the pattern of two months will raise their head, four months will roll over, six months will sit alone with hands propped forward, eight months will be able to sit steadily and crawl, and one year will be able to walk, but it should be considered according to the individual situation. Some infants have slower and later growth and development, and may not be able to sit at seven months, or holding the baby and not exercising is a situation that may lead to delayed motor development, and the baby should be allowed to train more and sit alone. Premature infant brain white matter injury, congenital brain development abnormalities and other diseases can also make the seven-month-old baby will not sit, when the baby exists in the motor development backward, parents need to pay attention. Seven-month-old babies who still can’t sit should be taken seriously, and it is recommended that they be seen by a specialist for evaluation and treatment.