A class of spacecrafts with fuel slosh would behave like a kind of underactuated system for they have to suppress the sloshing modes while controlling the spacecraft attitude. A sliding mode control approach wasproposed to stabilize the spacecraft which is transformed into certain normalized form. The designed controller can stabilize some states of the system, while other states can achieve the equilibriumdue to the system’s own characteristic. Finally, simulation results were presented to demonstrate the effectiveness and feasibility of the proposed controller.