Types of pain: 1. Acute pain: acute injury pain in soft tissues and joints, post-surgical pain, obstetric pain, acute herpes zoster pain, gout; 2. Chronic pain: intractable pain most commonly seen in trigeminal neuralgia, post-herpetic neuralgia and intervertebral disc herniation, etc. 3. Intractable pain: intractable pain most commonly seen in trigeminal neuralgia, post-herpetic neuralgia and intervertebral disc herniation, etc. 4. Cancerous Pain: advanced tumor pain, tumor metastasis pain 5, special pain categories: thrombotic vasculitis, intractable angina, idiopathic chest and abdominal pain Classification of pain level: 1, micro pain seems to be pain but not pain, often compounded with other sensations. 2.Light pain, pain limitation, pain reaction 3.Very pain, pain reaction is strong 4.Severe pain, pain is unbearable, pain reaction is strong. Classification of the nature of pain: The nature of clinical pain is diverse, including distension, stabbing pain, cold pain, burning pain, cramping pain, falling pain, hidden pain, wandering pain, fixed pain, pain in wind, pain in heat, pain in warmth and pressing, pain in fear of pressing and refusing to press, etc. The classification of pain forms: drilling-like pain, fracture-like pain, throbbing pain, tearing pain, pulling pain, pressure-like pain. Degree of pain: The World Health Organization (WHO) classifies pain into the following five degrees: degree: no pain Ⅰ: mild pain, intermittent pain without medication Ⅱ: moderate pain, continuous pain that affects rest and requires painkillers Ⅲ: severe pain, continuous pain that cannot be relieved by non-medication Ⅳ: severe pain, continuous pain with changes in blood pressure, pulse, etc.