If there is a nail-sized blood blister in the mouth, it is recommended to pick it after local disinfection and use chlorhexidine solution to rinse the mouth, and if the blood blister is caused by root stump or crown, it is also necessary to treat root stump and crown. If there is a nail-sized blood blister in the mouth, if it is an accidental bite or food trauma, it is recommended to disinfect the mouth with local iodophor, and then pick the blood blister with a sharp instrument to release the blood stasis in the blister, and then gargle with saline or chlorohexidine rinsing solution to maintain oral hygiene, and the blisters can generally heal by themselves in a week or so. However, patients should not pick through the blood blisters by themselves, and should be operated by a doctor. If the blood blisters are caused by bad restorations or root and crown stimulation, it is recommended to remove the bad restorations on the basis of the above treatment, and extract the root and crown. It is recommended to go to the stomatology department of regular hospitals, and be treated according to the condition after examination by the doctor.