First of all, we need to understand what is the law of height growth? According to the survey data of physical development of children aged 0~7 years old in 9 cities of China in 1985, the average height of newborns (lying length) was 50.2 cm for boys, of which about 95% was 46.8~53.6 cm; for girls, the average was 49.6 cm, of which 95% was 46.4~52.8 cm. Height growth is fastest in the first 3 months after birth, with an average of 3.0-3.5 cm per month, or about 10 cm in total. 4-6 months have an average growth of 2 cm per month. In the second half of the year, the average growth is 1.0~1.5 cm per month, so the height of the child grows 25 cm in the first year after birth, and the height is about 75 cm at the age of 1 year, which is 1.5 times of the height at birth. According to the law of pediatric height growth, the height of a normal child between 2 and 10 years old can be calculated by the following formula: height (cm) = age (years) * 5 + 80. Evaluating a child’s height development involves many factors and a more complex statistical treatment. There are several commonly used evaluation methods: percentile method, deviation method, and index method. To determine whether a child’s height is normal or not, it is first necessary to compare its height with that of a normal healthy child of the same age and sex. And this normal height is called the standard, which is a number calculated from the physical measurements of most representative healthy children, and is generally used to express the growth level of children by the standard deviation method and the percentile method. The standard method uses the mean and standard deviation as the evaluation “standard”, where height within the mean plus or minus one standard deviation is medium, within the mean plus one to two standard deviations is medium to high, and more than two standard deviations is high, which is tall; below the mean minus two standard deviations is low, which is Short stature. To evaluate the child’s height development, the actual measured value of the child’s height can be compared with the local standard. The objective comparison is used to initially understand whether the child’s height development is normal, what grade it belongs to, and whether there are signs of growth disorders. The so-called percentile method to evaluate height is to take out 100 boys or girls of a certain age group and arrange them according to the number of centimeters of height from small to large, with the small percentile value being low and the large percentile value being high, to find out the value of a certain percentile (with P as the code), which is often divided into the 3rd, 10th, 25th, 50th, 75th, 90th and 97th percentile. P3 represents the third percentile value, and P97 represents the 97th percentile value. Medical science classifies human growth and development into 5 levels based on the percentile method: those in the 25th to 75th percentile are medium. Those in the 75th to 97th percentile are upper middle class, those above the 97th percentile are upper class, those in the 25th to 3rd percentile are lower middle class, and those below the 3rd percentile are lower class and are short in stature. A child whose height is temporarily outside the normal percentile is not necessarily abnormal. It is not advisable to draw premature conclusions because children’s height growth varies from early to late. Some parents like to compare their children’s height with that of their peers, and therefore incorrectly conclude that their child is short or tall, which is not a scientific approach. However, if a child’s height is not within the percentile curve of the expected target height, it is necessary to look for the reason. Therefore it is helpful to combine parental height when using growth criteria to determine if a child’s height is normal. In the case of pubertal children, it is also necessary to combine the development of sexual characteristics, bone age, and other comprehensive indicators.