Stiffness of the tongue and poor speech may be oral submucous fibrosis, tongue swelling, cerebrovascular disease, and so on. 1. Oral submucous fibrosis: Oral submucous fibrosis is often associated with betel quid chewing, and the clinical manifestation is that the patient gradually feels the stiffness of the oral mucosa, tongue movement disorder. Therefore, it may cause tongue stiffness and poor speech. 2. Tongue swelling: tongue swelling invades the lingual nerve, which may cause tongue stiffness and poor speech. 3. Cerebrovascular diseases: Cerebrovascular diseases such as insufficient blood supply to the brain may cause tongue stiffness and poor speech. There may also be other pathologic factors, it is recommended to go to the hospital in time, under the guidance of the doctor to give targeted treatment or therapy.