Abstract. Atomic force microscopy (AFM) has been used as a new method to perform nanoscale measurements of the electrostriction coefficients in the lamellae structure of the ferroelectric P(VDF/TrFE) 73/27 copolymers. The result found shows that the electrostriction coefficient inside (in the middle of) the lamella crystals is 610-19(m2V-2), which is three times larger than that at the boundary, 210-19(m2V-2). To explain the dependence of the electrostriction coefficients with those two regions, some suggestions are proposed. By heat treatment at 140C during 2h, the sample changed its morphology as well as its crystallinity; the amorphous phase is much reduced and the degree of the crystallinity inside the lamellae is higher than that in the border. Also, it is suggested that in the lamellaes boundary the macromolecular chains come to an end, or one monolayer folds over the other layer. In this case, the electrostriction was suppressed due to the loss of surface energy in the lamellaes boundary. The achievements will supply a guideline to develop new and better devices for electromechanical and actuator applications.