Abstract: In this paper, a clouds model is applied to the triple inverted\|pendulum system with single motor. The objective is to keep the system in a state of dynamic balance. The qualitative control mechanism for inverted\|pendulum system is studied, and the formal representation of a clouds model for transformation between qualitative and quantitative knowledge is presented. This kind of representation reflects fuzziness and randomness contained in linguistic concepts, and can interpret uncertainty reasoning process rationally when several qualitative rules are activated simultaneously. The achievements can be used in space flying\|machines control and robots control. Moreover, they may have universal significance in revealing the transformation law between qualitative and quantitative knowledge.