In this paper, the effect of the reaction wheel dynamics as controller actuator in multi axis attitude maneuver of a 3D nonlinear flexible spacecraft is considered. In modeling of the actuator dynamic, friction, inertia and electrical subsystems are considered. The nonlinear robust control approach is composed of dynamic inversion and µ-synthesis schemes. To overcome the non-minimum phase characteristics, the controllers are designed by utilizing the modified output re-definition approach. In the design of controllers actuator saturation is considered. It is assumed that only three reaction wheels in three directions on the hub are used. To evaluate the performance of the proposed controllers, an extensive number of simulations on a nonlinear model of the spacecraft are performed. The performances of the proposed controllers are compared in terms of nominal performance, robustness to uncertainties, vibration suppression of panel, sensitivity to measurement noise, environment disturbance and nonlinearity in large maneuvers. In the disturbance modeling all terms such as constant, sinusoidal and impulse are considered. Simulation results show the effects of actuator dynamics and confirm the ability of the proposed controller in tracking the attitude trajectory while damping the panel vibration.