Objective To observe the effect of wearing an elastic soft occlusal splint on the stress of periodontal tissue in patient with bruxism. Methods A three-dimensional finite element model of jaw and dentition was created. Each tooth in the test area was loaded with the maximum adult occlusal force at 0°, 45°, and 90° with respect to the long axis of the tooth. 1 mm and 2 mm elastic soft occlusal splint were used, and the stress of the alveolar bone and periodontal ligament with and without elastic soft occlusal splint were analyzed and compared. Results Compared with the control group, 1 mm splint reduced the periodontal ligament stress of patient by an average of 16% and the alveolar bone stress by an average of 15%. After wearing a 2 mm splint, the patient's periodontal ligament and alveolar bone stress were reduced by 26% and 25% respectively. In all groups, the maximum stress of the periodontal tissue was on the buccal and lingual alveolar ridge crest, but the stress distribution was more uniform after using the soft occlusal splint. Conclusion The soft occlusal splint can be used to relieve occlusal stress and help eliminate the damage to periodontal tissue caused by the extra stress in bruxism.