Take penicillin preparation and dilute it with 0.9% saline as solvent, take 0.1 ml of the prepared skin test solution and hit the patient’s inner arm for skin test, use the other side of the limb as a negative control, and observe whether there is any allergic reaction in the patient within 20 minutes. If the center of the skin test appears to be a red halo, and more than 1cm, it is usually considered to be positive. Patients should also be asked if they have any adverse reactions such as chest tightness, wheezing, itchy skin, numbness of the limbs, etc. If the patient is found to be unwell, please take first aid measures immediately, and in serious cases, send them to the hospital promptly. This preparation process is sterile and the prepared solution is packed into sterilized vials and sealed for spare use. It has a shelf life of 24 hours at room temperature, after which it will be discarded. Penicillin skin test is a professional operation, must be carried out by professional nurses or doctors, do not do it by yourself.