The development of secondary sexual characteristics in girls before the age of 8 is clinically diagnosed as precocious puberty, and the main symptoms include: 1. Breast development: it can be manifested as a flatter chest at the beginning, the appearance of breast nodules, and then further development of breast nodules; 2. Changes in external genitalia: pigmentation, secretions, and changes in pubic hair can appear; 3. Changes in subcutaneous fat: such as fat accumulation in the buttocks and legs; 4. Others: armpit hair, high pitched voice, and even the first menstruation at a later stage may appear. If the above symptoms are found, it is recommended to seek medical attention and active treatment.