Dry socket is a postoperative infectious disease after tooth extraction, mostly caused by bacterial infection of the alveolar bone after wisdom tooth extraction, mainly related to excessive extraction trauma and post-extraction wound infection. The main symptom of dry socket is severe pain, mostly seen two to three days after the extraction, in the extraction area, sometimes radiating to the auriculotemporal or submandibular area. The pain is usually difficult to be relieved by the commonly used pain relieving drugs. The extraction socket is empty, with missing blood clots or a corrosive grayish-white blood clot with a distinct foul odor, and the exposed bone surface can be probed with a probe and accompanied by significant pain. The treatment of dry socket should be a thorough debridement to isolate the external infection from the socket and to promote the growth of granulation tissue in the socket to heal the wound. The diet for dry socket should be light and liquid, avoiding foods that are too hot or too hard to prevent new blood clots from falling off. Do not eat spicy and stimulating foods. In conclusion, dry socket is an infectious disease after tooth extraction, mostly associated with severe pain, and requires thorough debridement and a light diet.