Oral blood blisters are a common oral disease. Recurring oral blood blisters seriously affect our daily life, and severe oral blood blisters may also be cancerous. Although the surface symptoms of oral blood blisters look similar, they are actually different. Oral blood blisters are commonly associated with oral ulcers. Oral blood blisters should be distinguished from traumatic mucosal blood blisters and thrombocytopenic purpura oral blood blisters. Differential diagnosis: 1, traumatic mucosal blood blisters: often caused by hurried chewing of large pieces of dry, hard food or swallowing too fast. If the blood blister occurs in the buccal mucosa due to inadvertent chewing is generally small, with a diameter of about 0.5 cm, heals quickly and rarely becomes an erosion or ulcer. However, if it is due to the unilateral soft palate, hard and soft palate junction, the uvula and tongue and palate arch and other parts of the blood blister is larger in diameter, sometimes up to 2-3 cm large, there is a foreign body feeling, the blood blister is easy to rupture and pain is obvious. 2, thrombocytopenic purpura oral blood blisters: recurrent blood blisters, blood routine shows a decrease in platelet count, coagulation function is reduced. It can occur in any part of the oral mucosa, with the lips, cheeks and tongue being the most common, and in severe cases it can spread to the pharyngeal mucosa.