The photoluminescence and temperature sensing properties based on down-shifting emission of Pr3+-doped (K0.5Na0.5)NbO3-yCaTiO(3) (KNN: yCT) diphasic materials were systematically investigated. Under 447-nm excitation, Pr3+-doped KNN: yCT samples exhibited significantly enhanced red emission at 603nm assigned to (D2H4)-D-1-H-3 transitions of Pr3+ ions. The red emission intensities reached the optimum value with y=0.05 near the polymorphic phase transition region. The origin of the enhanced red emission is mainly ascribed to the doping-induced lattice symmetry change. The energy level transitions from the typical f-f transitions to the valence-to-conduction transitions were observed as CaTiO3 concentration increases above a critical concentration of y=0.05. Furthermore, the sample with y=0.05 also possessed excellent temperature response properties in a wide temperature range 300-473K and the maximum sensing sensitivity was 0.016K(-1). The Pr3+-doped (K0.5Na0.5)NbO3-yCaTiO(3) red emission materials with admirable intrinsic piezoelectric properties may have important technological promise in novel multifunctional devices.