This paper presents the results of a cost optimization problem for two stage helical gearboxes with second stage double gearsets. To do that, a simulation experiment was performed. The experiment consists of nine input parameters including the total gearbox ratio, the wheel face width coefficient of the first stage, the coefficient for determining the wheel face width coefficient of the second stage, the allowable contact stress of the first and second stage, the output torque, the cost of gearbox housing, the cost of shaft and the coefficient for determining the gear cost. Also, the experimental results were analyzed by the Analysis of Variance (ANOVA) method with the help of the Minitab 19 software. Moreover, a regression model to find the optimum gear ratio of the first stage was proposed.