Abstract: To obtain good transmission quality, it is necessary to design the tooth profile of spiral bevel gears to control their contact characteristics. The tooth profile was designed through the construction of spiral bevel gear conjugate tooth profiles and ease-off tooth surface. The preset transmission errors were introduced in the solution of conjugate tooth surface, and a correlation model between the contact area morphological parameters and the ease-off tooth surface modification was established by using the relative curvature and line conjugate surface characteristics. All the contact parameters were accurately controlled. A designed method of ease-off tooth surface and contact area shape based on tooth surface characteristic conjugate contact line modification and interpolation algorithm was proposed, by which the tooth root due to modification of the factors that lead to the failure of solving undercutting can be avoided. At the same time, this method can be used to design the entire ease-off tooth surface by only a small number of feature points, which can significantly improve the computational efficiency. Finally, the correctness of the method were verified by the tooth design examples and tooth contact analysis.