The term “lisp” usually refers to slurred speech, and needs to be analyzed according to the individual’s age and other clinical manifestations. If a child has slurred speech, it may belong to the phenomenon of stuttering, some of which will gradually improve with age, while some will need rehabilitation training to improve their slurred speech. Some adults or elderly people with slurred speech need to focus on several diseases, including facial paralysis and neuritis behind the mouth caused by skewed corners and slurred speech. In addition, the elderly should pay attention to the slurred speech caused by cerebral infarction. Therefore, once slurred speech occurs, it is important to go to the hospital for timely diagnosis and treatment.