To explore new relaxor-PbTiO3 systems for high-power and high-temperature electromechanical applications, a ternary ferroelectric ceramic system of Pb(Lu1/2Nb1/2)O-3-Pb(In1/2Nb1/2)O-3-PbTiO3 (PLN-PIN-PT) have been investigated. The phase structure, dielectric, piezoelectric, and ferroelectric properties of the as-prepared PLN-PIN-PT ceramics near the morphotropic phase boundary (MPB) were characterized. A high rhombohedral-tetragonal phase transition temperature TR-T of 165 degrees C and a high Curie temperature T-C of 345 degrees C, together with a good piezoelectric coefficient d(33) of 420 pC/N, were obtained in 0.38PLN-0.20PIN-0.42PT ceramics. Furthermore, for (0.8-x)PLN-0.2PIN-xPT ceramics, the temperature-dependent piezoelectric coefficients, coercive fields and electric-field-induced strains were further studied. At 175 degrees C, their coercive fields were found to be above 9.5 kV/cm, which is higher than that of PMN-PT and soft P5H ceramics at room temperature, indicating PLN-PIN-PT ceramics to be one of the promising candidates in piezoelectric applications under high-driven fields. The results presented here could benefit the development of relaxor-PbTiO3 with enhanced phase transition temperatures and coercive fields.