This paper deals with the problem that the piezoelectric material can be made into driver elements by utilizing its inverse piezoelectric effect-i.e. when voltage is impressed across the material, the deformation of the piezoelectric element will be caused because of the effect of electric field. The intelligent cantilever, if the piezoelectric drivers are fitted symmetrically, will produce the pure bend control moment under the effect of the control voltage with opposite polarities. Through analysis of the strain distribution over the transverse section of the intelligent cantilever beam, the theoretical calculating formula for the effective bending moment caused by piezoelectric driver train is deduced and two methods of measurement of the effective bending moment are presented.