Bracket type posture adjustment mechanism is widely used in aircraft assembly field to adjust the position and posture of the work-piece. Due to the large mass and inertia of the bracket, the kinematics control is difficult and dynamic control needs to be introduced. Independent variables of the posture parameters of the bracket type parallel posture adjustment mechanism in the posture reverse solution and the independent variables of the driving parameters in the posture positive solution were determined. Based on the independent variables, the positive and inverse solutions of velocity and acceleration were analyzed. Newton-Euler method was used to model the dynamics of a new type of three-degree-of-freedom redundantly actuated automatic drilling and riveting bracket type parallel posture adjustment mechanism. Combined with the analysis of the deformation coordination of the telescopic barrel, the posture error and structural error analysis of the posture adjustment mechanism, the dynamic model also took into account the influence of the sliding pair friction of the positioner. Then, the supplementary equations related to the force of the spherical joint, the deformation of the top of the telescopic cylinder, the position and posture error of the posture adjustment mechanism and the position error of the center point of the spherical joint was established. It increased the number of constraint equations in the dynamic model. The dynamic model is mutual verified by Matlab and Adams. Compared with the existing dynamic model, the precision of driving force solution of the dynamic modeling method is more accurate. It proves the validity of the modeling method and can be applied to other types of dynamic control of parallel mechanisms based on positioners.