Abstract: To simplify the designing and manufacturing of the double lead spiroid worm-gear drive,a new concept and way of a double lead spiroid worm-gear drive are proposed.For the new spiroid worm-gear drive,transmission principle and the correct meshing transmission conditions are demonstrated in detail.A calculation example that illustrates the developed theory is provided and simulation of meshing by a computer program based on the CATIA is developed to determine the transmission principle.It's very simple for the engagement principle of the new type gearing.So that designing and manufacturing the gear pair also are easy, compared with designing and manufacturing the conventional spiroid worm gearing.And there is larger load bearing capacity with the beeline contact of the flanks.