The relationship between the deflection displacement and blocking force of piezoelectric knitted selecting element is analyzed, the relation between the force and displacement with inactive layer thickness ratio is calculated with the finite element software, and the performance differences by using carbon fiber、steel and aluminum as the inactive layers are compared. The results show that the deflection displacement is decreased gradually with the thickness ratio, while the blocking force is gradually increased with the thickness ratio. When the ratio is less than 0.8, the performance of steel is better than that of carbon fiber and aluminum; when the ratio is greater than 1, the performance of the steel is decreased, and the performance of aluminum is increased. The comprehensive performance of the knitted selecting element is more stable when the carbon fiber is selected as the inactive layer.