Purpose. To analyze the stress distribution and displacement of alveolar ridge mucosal tissue when Biofunctional prosthetic system (BPS) dentures were dislocated under three conditions. Materials and Methods. CBCT was used to obtain the data of the patient's jaw, and the patient's BPS scan data was gained through the oral scanner. Through Mimics, Geomagic Studio and Unigraphics NX software, the CT data files were built into 3D finite element models (FEM) of the upper and lower edentulous jaws, mucosa and BPS complete dentures, then analyze the stress distribution and mucosal tissue displacement caused by ridge mucosal tissue when BPS dentures were dislocated under three conditions (BPS denture dislocation along the anterior alveolar ridge, BPS denture dislocation caused by the left posterior teeth biting hard food or anterior teeth biting hard food), respectively. Results. In general, under the three different circumstances, the value in the relatively large area of the maxillary and mandibular equivalent stress was similar, but the deformation value of the mandibular mucosa was significantly higher than that of the maxillary mucosa. Conclusion. When BPS complete denture is dislocated, the stress distribution of the mucosa under the base of the maxillary and mandibular dentures is uniform and extensive, and the stress distribution of the palatal mucosa is small. In comparison to the dislocation of BPS dentures that were removed and worn independently, the mucosal stress distribution was more uneven when BPS dentures were subjected to biting hard food, resulting in greater deformation.