Objective: To investigate the influence of occlusal splint thickness on mandibular movement. Methods: Stabilization occlusal splints of 3, 5 and 7 mm thickness were respectively used during clenching from light contact in intercuspal position and the movement of condyles and incisor point were recorded in 5 healthy subjects. Results:The condyles moved anteriorly and superiorly without wearing occlusal splint. When wearing the occlusal splints the condyles displaced anteriorly and inferiorly. The distance of displacement increased gradually with raising the thickness of splint, though the significant difference was just found in right condyle in superior- inferior movement. The condyles went again on a path of anterior and superior direction when subjects clenched from the displaced position. In right condyle the displacement was significantly greater at 7 mm splint than that at 3 mm splint both in anterior-posterior and inferior-superior direction, while in left condyle only in anterior-posterior direction. Meanwhile, the incisal point movement was larger at 7 mm splint than at 3 mm splint in inferior-superior direction. In tapping movement there were no significant differences in condyle movement between the different thickness of occlusal splint. However, the coefficient of variation in total cycle time was the greatest when wearing the splint of 7 mm. Conclusion: Occlusal splint of 7 mm has greater effect than that of 3 mm on condyle movement, but no obvious difference with occlusal splint of 5 mm. When occlusal splint of 7 mm is inserted, the stability of condyle might be influenced during tapping movement.