Identification of common causes of hair loss: 1, non-inflammatory and non-scarring alopecia such as baldness, androgenetic alopecia, stress alopecia and drug or chemical toxic alopecia (divided into resting alopecia and anagen alopecia), etc.; 2, alopecia with lesions but without scars such as seborrheic alopecia, tinea capitis, stage II syphilis, etc.; alopecia with frequent lesions and scars such as DLE, follicular lichen planus, mucin deposition alopecia and scars Acne alopecia, etc.; 3. Pediatric alopecia is mostly congenital or genetic; systemic diseases leading to alopecia such as thyroid disease, plucking fetish, malnutrition (e.g. weight loss), etc. Examination: hair pulling test, Woo’s lamp examination, fungal microscopy and culture, hair root or hair stem microscopy study; if necessary, skin lesion biopsy or add direct immunofluorescence examination, thyroid function test, trace element test, syphilis serologic reaction, etc. Treatment: 1, etiology or trigger treatment: such as baldness tell relaxation decompression, ringworm antifungal treatment, syphilis long-acting penicillin treatment, DLE select hydroxychloroquine or reaction stop treatment or local (1) Anti-inflammatory and anti-proliferative anti-itch drugs such as topical strong glucocorticoids or intra-dermal injection of Depo-Provera (e.g., baldness, non (1) anti-inflammatory and anti-proliferative drugs include external strong glucocorticoids or intra-dermal injection of Depo-Provera (e.g., baldness, non-infectious or neoplastic inflammatory or proliferative lesions), oral vincristine (anti-proliferative), oral melatonin (anti-inflammatory), prednisone 30-40 mg/day (severe inflammation); (2) hair growth promotion drugs include external drugs such as 2% minoxidil, vincristine cream; internal drugs such as bofadil (for male androgenetic alopecia), amphotericin or spironolactone (for female androgenetic alopecia), Chinese patent medicines (e.g. 3, other treatments: light therapy with laser hair growth instrument (to improve local blood circulation), 308nm excimer light (to suppress local immune response), surgery with autologous post-occipital hair follicle separation and transplantation, wig transplantation, abscess sinus excision, etc.