We studied optical properties of $Al_{1-x}In_xN$ films. Films were grown on GaN by metalorganic vapor-phase epitaxy. The AlInN layer was grown on GaN layer with an $alpha$-Al$_2$O$_3$substrate. X-ray diffraction, optical absorption spectroscopy, photoluminescence(PL) and reflection high energy electron diffraction(RHEED) measurements of AlInN showed that the crystalline quality of $Al_{1-x}In_xN$ layer was improved around x=0.17, at which the lattice constant was matched to the GaN and the band gap of AlInN is larger than that of GaN.