The Pb (In1/2Nb1/2) O3–Pb (Mg1/3Nb2/3) O3–PbTiO3 (PIN-PMN-PT) crystals were studied as function of phase and orientation. The properties, including the Curie temperature TC, ferroelectric-ferroelectric phase transition temperature TR/O-T, coercive field, and piezoelectric/dielectric responses, were systematically investigated with respect to the composition of PIN-PMN-PT crystals. The Curie temperature TC was found to increase from 160 to 220 °C with ferroelectric-ferroelectric phase transition temperature TR-T and TO-T being in the range of 120–105 °C and 105–50 °C, respectively. The piezoelectric activity of PIN-PMN-PT crystals was analyzed by Rayleigh approach. The ultrahigh piezoelectric response for domain engineered  (1600–2200 pC/N) and  (830–1550 pC/N) crystals was believed to be mainly from the intrinsic contribution, whereas the enhanced level of piezoelectric and dielectric losses at the compositions around morphotropic phase boundaries (MPBs) was attributed to the phase boundaries motion.