The reason which produce the vibration and noise during the gearbox meshing process is expounded.The-time varying dynamic model of gear transmission is build.The influence of meshing stiffens and transmission error on vibration response is analyzed.Based on this the noise due to vibration is quantitative calculated by using Kato method.Computation results indicated that the semi-sphere noise radiation model is more precisely than the sphere one on the gear-transmission analysis.Finally

the experiment proved the former inference.It is shown that this method is a good ideal method for estimate the noise due to gear vibration

it provides basis for low noise design and noise-decreasing of gear system.