The 12-year-old girl’s irregular menstruation, 11 days of menstruation did not clean, mostly considered to be physiological factors, the gonadal axis development is incomplete and so on. 12-year-old girls are still relatively young, may be just a short time after menstruation, the gonadal axis is not yet fully developed, at this time the center of the positive feedback mechanism of estrogen is not yet mature, so the menstrual cycle is often irregular, in the first menstruation, after 5 ~ 7 years to establish a regular cycle ovulation, menstruation is gradually normal. 12-year-old girls in puberty, adolescent girls will occur greater psychological changes, easy to excitement, coupled with the usual life, due to the pressure of study and other mental factors can easily lead to abnormal menstruation. It is recommended that girls relax, adjust their daily routine and diet, and do not be too anxious and worried. If the bleeding does not stop, it is recommended to consult a doctor.