In this study, Lu2O3:Eu(3+) inverse-opal-photonic crystals (IOPCs) with controllable lattice constants were fabricated using a polymethylmethacrylate (PMMA) template. The modification effect of PC on the (5)D0-(7)F(J) and (5)D1-(7)F(J) (J = 1-6) transitions were systemically studied by emission spectra, luminescent dynamics and the temperature-dependence. It is significant to observe that the increase of (5)D0-(7)F(J) radiative lifetime for Eu(3+) ions (30%) in contrast to the reference sample was mainly due to modulation of the effective refractive index, rather than the density of optical states. The spontaneous decay rate in (5)D1 increased linearly with the decreasing lattice constants, which was due to the change in (5)D1-(5)D0 nonradiative relaxation of the IOPC samples. The temperature quenching of Eu(3+) ions in the IOPCs could be suppressed considerably more than the reference. On this basis, dual functional refractive index detection with infiltrated solutions was realized by monitoring the variation in the photonic stop band (PSB) and the lifetime of (5)D0-(7)F2 transition of the Lu2O3:Eu(3+) IOPCs. This work shows that the Lu2O3:Eu(3+) IOPCs present highly modified photoluminescence properties and are promising candidates for dual-functional refractive index sensing application.