Physiological reasons for not having menstruation at the age of 14 can be observed for the time being, but pathological reasons for the lack of development of secondary sexual characteristics need to be identified and actively treated. 1. Physiological phenomenon: the general age of menarche is between 11 and 16 years old, but due to the influence of nutrition, body weight, heredity and other factors, some girls may be delayed until the age of 16, but there is the development of secondary sexual characteristics, such as breast eruption, growth of pubic and axillary hair, etc., which can be temporarily observed under the guidance of a doctor. 2. Pathological causes: For those who do not have the development of secondary sexual characteristics and do not have menstruation at the age of 14, it is a pathological phenomenon, and physical examination, pelvic ultrasonography, CT or magnetic resonance examination, chromosome examination and hormone measurement are needed to clarify the causes. If gonadal dysgenesis is present, sex hormone supplementation, such as estradiol valerate, should be prescribed. If there are hypothalamic or pituitary tumors, timely surgical treatment is needed. If a girl is 14 years old and does not have her period, it is recommended to go to the hospital, complete the relevant examinations, and under the guidance of the doctor to identify the cause, targeted treatment, so as to avoid delays in the condition.