In this paper,the quantitative restraint conditions of choosing scaling factors are derived.On this basis,the contradictory of giving hardly consideration to both the control system’s dynamic and static characteristics is discussed in choosing scaling factors.For this reason,a variable gain fuzzy control method is presented .Through numerical simulation, it is proved that this method is by far better than the fixed gain method in giving consideration to the dynamic and static characteristics. And this method adapts better itself to the variation of the parameters of controlled object than the fixed one.