The performance of four-year-old developmental delay mainly in physical development, speech and communication, motor development can not reach the normal age of the standard development level, the development of children of the same age lag behind. 1. Physical development: due to environmental and genetic factors, the child’s height and weight are significantly lower than the normal average of two standard deviations of the same age and sex, four-year-old children, the normal height growth rate of an average of five centimeters per year, when this standard is not reached, it can be manifested as a low body weight, emaciation, or growth retardation and so on. 2. Verbal communication: 4-year-old children can normally sing children’s songs, tell stories, and say their own names, etc. If the child lags behind in verbal communication ability compared to people of the same age, can only use words to communicate, can’t use sentences to express themselves, has poor language comprehension, and can’t communicate with family members normally, then it is considered to be a delay in verbal development. 3. Motor development: including gross motor and fine motor, 4-year-old children can normally run, jump and go up the stairs without holding the railing, and can draw vertical straight lines, circles and thread beads under the guidance of parents, but children with delayed motor development cannot complete these simple movements independently, so they need to be vigilant. If any of the above symptoms appear, it is recommended to go to the hospital in time for early and regular treatment.