Boys generally develop to the age of 17-18 weeks, they will be mature: boys generally from the age of ten to 13 years old, into puberty, the biggest feature is the testicles become larger, thicker and longer penis, androgen secretion increased; 13-14 years old, belong to the voice change period, the voice becomes thicker, laryngeal nodes become larger, body hair flourishing, ejaculation at night; 16-17 years old, will grow a beard, pubic hair into a shuttle-shaped distribution; 17-18 years old, muscular, low voice, loud, and gradually developed into a strong man.