Gears are rotating mechanical parts with excellent power transmission efficiency and are widely used in machine tools, automobile, industrial machinery, and aviation industries. To enhance the performance of the gear, optimized design of the gear geometry is paramount. In this paper, we optimize the geometric tooth profile of helical gears which are among the gears of the transfer case gearbox by using the finite element program, Romax Designer to model and analyze the load and gear teeth of the gearbox power transmission system. The optimized gears were fabricated and compared to the results of the gear tests.