Based on the generalized finite element method and the substructure method,a dynamics model of the double gearbox transmission system coupled by the diaphragm coupling is established. The dynamic meshing forces and the dynamic bearing forces are calculated through the Fourier method,which are then compared with the results without considering the coupled effects. The result shows that the coupled effects on meshing pairs are small,while effects on bearings are more significant especially on those close to the coupling,and when considering the coupled effects,the dynamic meshing force and dynamic bearing forces emerge other frequencies,but the amplitudes of them are small.