Summary: Taking a kind of unicycle robot, which is driven to keep longitude stability and lateral stability by a wheel and a motor driven disk respectively, as an object to be controlled, the dynamic model of the robot system is established, and the system equation is linearized at the equilibrium point. Two linear models are obtained, which are decoupled in longitude and lateral. Then the fuzzy controllers are designed based on the fusion function aiming to the two systems respectively. The method can decrease the number of fuzzy rules and avoid the rule’s explosion. The simulation results show that the controller allows the system the achieve the balance and the steering of the movement l.