Large Pb(In1/2Nb1/2) O-3-Pb(Mg1/3Nb2/3)O-3-PbTiO3 (PIMNT) crystals with the size of Phi 55 x 100 mm have been successfully grown by the Bridgman method. The as-grown PIMNT crystals not only show excellent piezoelectric properties but also high Curie temperature, high rhombohedral tetragonal phase transition temperature and high coercive field. Domain structure and phase transition process of PIMNT crystals were observed in-situ by means of polarizing light microscopy (PLM). As for the rhombohedral PIMNT crystals, the rhombohedral tetragonal phase transition and the ferroelectric to paraelectric phase transition could be observed obviously in the heating procedure whereas these phase transitions could not be seen clearly in the successive cooling procedure. As for the tetragonal PIMNT crystals, the ferroelectric to paraelectric (T-C) phase transition could be observed obviously in both the heating and cooling procedures. This may attribute to the difference in the relaxor ferroelectrics and normal ones. (C) 2010 Elsevier B.V. All rights reserved.