Taking the wind power speed-increasing gearbox of load distribution type with two-stage planetary one-stage parallel axis as study object,considering the meshing stiffness,supporting stiffness and torsional coupling stiffness of the planetary gear mechanism and parallel shaft gear at low speed stage,medium speed stage and high speed stage,the dynamics model with considering the radial direction deviation and torsion deviation is established.The inherent characteristic of the model is analyzed,the vibration mode is divided into displacement vibration modal and torsional vibration modal and the vibration characteristics of each modal are obtained.Through changing the numerical size at all stages torsion coupling stiffness,the influence law of torsional coupling stiffness numerical variation on the coupling vibration state between low speed stage and medium speed stage,and medium speed stage and high speed stage is obtained.Through changing the connection types of all stages,the gear at all stages running at the coupling vibration condition can be decreased or avoided.