The phenomenon of girls starting to grow pubic hair at the age of 9 is mostly a normal manifestation and a symptom of girls entering puberty. Generally speaking, precocious puberty usually refers to girls before the age of 8 years of age to appear the symptoms of secondary sexual characteristics, girls are mainly manifested in breast development, pubic hair and armpit hair appear and menstruation. And girls start to grow pubic hair at the age of 9, which is a normal age phenomenon, generally do not need special treatment. If the above symptoms appear before the age of 8, the possibility of precocious puberty should be highly suspected. The risk of precocious puberty can be minimized by avoiding excessive intake of hormone-containing foods or drugs. It is recommended that girls who develop pubic hair should pay more attention to the care of their children, keeping the local skin clean and preventing infections.