In order to reduce NV level of gears and optimize load distribution along gear trace

the misalignment of meshing must be controlled.The equation about helix slope deviation of pinion and wheel is established by simulation result

based on the misalignment caused by helix slope deviation must be equal with the misalignment caused by shafts and gears deformation.The noise of transmission assembled with five pairs of third gears containing different helix slope deviation is tested

and the static transmission errors of gear are analyzed.Noise variation of five gears is the same as that of their static transmission error

it was illustrated that teeth-matched about helix slope deviation could improve the NVH performance of transmission.