It is studied on the influence of contact path on meshing behavior of gears and their mutual relationship.The program of Gleason using widely in the manufacturing has been improved on achieving the pre-control of the behavior of tooth contact by using the proportional modification.Finally the comparison experiments on the meshing behavior of the conventional design and the bias-in one are done.It are concluded that the design using in-in of contact path can improve the dynamic meshing performance of gears.