1.Endocrine hormone examination: The commonly done examinations include sex hormones (testosterone, folliculopoietin, luteinizing hormone, estradiol, lactogen), thyroid hormones (fT3, fT4, TSH). Among them, testosterone is the most important hormone for men, which plays an important role in penile erection and maintenance of libido. Folliculopoietin and luteinizing hormone can help us to determine pituitary and testicular pathologies. The actual testosterone can be decreased by the lesions of pituitary gonadal axis and thyroid gland, as well as testicular insufficiency. 2, blood sugar, lipids, blood pressure: high blood pressure, high blood lipids, high blood sugar is an important factor that damages the endothelial cells of blood vessels, which is a risk factor for both cardiovascular and cerebrovascular diseases, as well as erectile dysfunction. Therefore, regulating lipids, lowering blood pressure and controlling blood sugar is to treat erectile dysfunction at the root.3. NPT (Nocturnal Penile Erection Test): Patients continuously record the number of penile erections and the duration of erections in the sleep state. This is the most effective method to identify psychological and organic erectile dysfunction in clinical practice. The above is a non-invasive test, which is painless for patients and easy to operate, and is widely used in clinical practice. 4. Color Doppler examination of penile corpus cavernosum: This is a necessary test for patients with vascular erectile dysfunction. It is an invasive test, which requires the signing of an informed consent form, the injection of drugs into the penile corpus cavernosum to induce erection, and the observation of penile arteries and veins for lesions through color ultrasound. It is suitable for patients with erectile dysfunction induced after penile trauma, sclerosis of the penis, and long-term regular oral PDE5 inhibitors with poor results.5. Penile cavernosography: It can clarify the location of penile arteriovenous fistula. After signing the informed consent, contrast is used and the film is taken under X-ray. There may be abnormal penile erection, subcutaneous bruising and infection after the procedure.6. Erectile nerve testing: including ball cavernosal reflex latency and pubic evoked potentials. It is non-invasive and requires close cooperation from the patient.