Children will probably grow sweat hair around 8~10 years old, but the growth of sweat hair needs to be judged according to the individual’s physical condition, and there are some individual differences. 1. Some children at the age of 8~10 years old due to the gradual development of the body, the body’s hormone secretion, may lead to hair follicle growth and development speed up, so there will be symptoms of sweat hair development,. 2. There are also some children who are affected by genetic factors and will have obvious sweat hair at a relatively young age or do not have obvious sweat hair growth. All of the above is normal, as long as it does not affect the normal life of children, generally do not have to worry. Children should be monitored for physical symptoms and seek medical attention if any abnormality is found.