To small spacecraft with movable appendage, the rotation of appendage may badly disturb the spacecraft's body and worsen the performance of attitude control system. This paper takes a small spacecraft what has a rotatable paraboloid antenna and three flexible solar panels as an example, presents the dynamic model of it. The open-loop character of this small spacecraft is also analyzed by simulation. In order to improve the control performance, a variable structure control law is designed. Based on the control law, a close-loop simulation of the attitude control system is implemented. The results indicate that the variable structure control law can effectively improve the attitude control performance of small spacecraft with movable appendage.