Abstract: Based on Hamilton’s principle, the dynamic model of flexible spacecraft consisting of a rigid central body and a flexible beam, is derived by Timoshenko beam theory. Then dynamical modeling and control of the flexible spacecraft during attitude maneuver are investigated. Controller is designed by controlling boundary conditions of tip of Timoshenko beam. The proposed controller can stabilize the system exponentially. The simulation is presented. Variable rules of angular displacement of hub and tip trajectory of flexible beam are discussed. Highly robust variable structure controler to control flexible spacecraft is thusly given.