Gear geometry is critical to the transmission performance. It not only affects the relative motion characteristics, lubrication, efficiency, and loading capacity but also affects the noise and vibration, as well as working reliability of system. The generating principles of one kind of torus involute (TI) gears is presented in this paper. The mathematical model and profiles equation of torus involute gears are derived and the profiles equation and its parameters are proposed. The correct meshing condition and tooth contact analysis (TCA) are analyzed. The loading capacity including contact stress and bending stress, etc., are proposed after compared with cylindrical spur gears. One pair of TI gears is machined according to the generating principles. The analysis results show that the TI gears can reduce the contact stress efficiently and it can effectively improve the bending strength of convex involute gear while the bending strength of concave TI gears is not significantly affected.