Ferroelectric PbMg1/3Nb2/3O3-0.33PbTiO(3) (PMN-0.33PT) polycrystalline thin film near MPB was grown on Ir with LaNiO3 buffer layer by pulsed laser deposition technology. Piezoresponse force microscopy (PFM) was employed to investigate the role of grain boundary on the domains formation and their local physical properties in PMN-PT thin film. Unusual piezoresponse behaviors were firstly observed across the grain boundary of PMN-PT thin film via PFM. Such abnormal phenomenon is ascribed to the structural incompatibility-induced local stress across the grain boundary, which gives a deep influence on the local imprint behavior of PMN-PT thin film. (C) 2011 Elsevier B.V. All rights reserved.