In this study, a method based on the results of an optimization study on the influence of the main design parameters on the total cost of a worm-helical gearbox was proposed. Specifically, ten main design parameters were investigated to find their influence on the optimum gear ratio of the worm set u1. To do that, a simulation experiment was designed and implemented by a computer program. The results showed that in addition to the influence of the input parameters, their interactions also have important effects on the response u1. Finally, a regression model is proposed and its reliability is confirmed through the results obtained.