Abstract: Objective:The character of stress distribution in the mandible in a normal huamn being during centric occlusion was analysed, and the normal standard value for symmetry of stress distribution in a human mandible was determined.Methods:The three-dimensional finite element model was developed by CT scanning and Auto-CAD technique. The stress analysis was done by three-dimensional finite element method. Results:The stresses of various positions or regions in the mandible of normal human being are distributed unequally. There are differences in the feature and value of the stress, but the stress of corresponding region in bilateral mandible is in symmetric distribution. In each region of the mandible, the stress symmetry is the best in the bilateral coronoid process, and it is the worst in the bilateral condyle. The P_90% of D value related with symmetric index of maximum principal stress and minimum principal stress considered of 20% and 25% seperately in a normal human mandible.Conclusion:The complexity of geometry, material properties, loading pattern and movement way in the mandible determined the difference of stress feature and value in its various regions. The anterior and lateral surface of condyle and so on were the main loading regions. The symmetry of shape, structure and composition in normal bilateral mandible made its stress distribution balanced. The condyle might be the easiest to be affected by the unbalanced factors and produce an abnormality of stress distribution.