The detailed temperature dependent optical properties in double perovskite type Nd2CoMnO6-SrTiO3 (NCMO-STO) thin films have been investigated the experimentally grown epitaxial thin films on STO substrates using pulsed laser deposition technique. At first order room temperature, a Raman spectrum of NCMO/STO thin films are measured in unpolarized geometry using 488 nm laser excitation and confirms its monoclinic bulk like crystal structure. Temperature dependent Raman spectra confirms the appearance of a sharp, intense phonon mode below magnetic ordering, signifies structural phase transition accompanied by magnetic transition. The phonon mode position and line-width are fitted by anharmonic model and found to be strongly softened phonon mode position below TC and strong spin-phonon coupling in the system. The excitation spectrum and the bandgap in NCMO film confirms the yellow emission resulting from energy transfer within the non- centrosymmetric structure.