Double-Enveloping Reducers are used widely in various industries. In this study, a procedure is developed to analyze the geometric and kinematic properties of such a rotational reducer. In the mechanism, the globoidal worm profile is derived by using the sweeping method and the profile of the globoidal worm wheel is obtained by employing the screw theory. Based on Standards of the American Gear Manufacturers Association (AGMA 6030-C87), the involved parameters in designing and analyzing the reducer are revealed. Finally, the transmission errors based on tooth the contact analysis (TCA) are also reported.