Dynamic equations describing the attitude motion of flexible spacecraft with scissored pairs of control moment gyroscopes are established. A nonlinear controller is designed to drive the flexible spacecraft to implement three-axis large-angle attitude maneuvers with the vibration suppression. Singularity of three orthogonally mounted scissored pairs of control moment gyros is analyzed. A new moore-penrose steering law is designed based on the synchronization constraint of gimbal angles. To improve the synchronization performance, an adaptive nonlinear controller is designed for each pairs of control moment gyros. Simulation results show the validity of the controllers and the steering law.