Load distribution factors among the teeth under different contact ratio were computed by the elastic-plasticity contact finite-element method, the normal curvature radius on the contact points were calculated by the theory of gear engagement, and simplified models of single and total length of contact line were established. Based on the Hertz model, contact stress analysis formula of the tooth which carries the maximum load was deduced, and contact stress formula of the teeth was deduced. The finite-element model of the worm gears was established, stress distribution status along the contact line and load distribution factor among the teeth were analyzed under different loads. At last, the contact stress analysis formula and finite-element method were compared by the example.The result showed that the results of the two method are very near, the result of the former higher than the later’s about 10%~25%.
