Abstract:The finite element model of variable tooth thickness involute gear enveloping hourglass worm drive was established. The influences of different loads and assembly errors on the contact state and stress of tooth surface were analyzed, and the contact spots and transmission performance were tested. The results show that the contact spots of the transmission pair are consistent with the contact states, and the tooth surface stress is distributed along the contact line and becomes larger with the increase of the load; among the four assembly errors,such as center distance error, axial offset error of the involute gear, axial offset error of the hourglass worm, and shaft angle error, the influence of the axial offset error of the variable tooth thickness involute gear is small, the center distance error has a significant effect on the contact state and stress of the transmission pair tooth surface, the axial offset error of the hourglass worm and intersection angle error have influence on the stress, the installation error of the last three items should be minimized; the transmissionefficiency of the prototype is between 51%~67%, and the forward rotation transmission efficiency is slightly higher than the reverse.