The molecular structure and spectral properties of a novel acylhydrazone ligands 2-hydroxy-naphthaldehyde-5-chloro-salicyloylhydrazone (H3L) and its Sn metal complexes [(n-Bu2)Sn(HL)] in solution, crystal and thin films were investigated by using steady state and time resolved fluorescence spectrum. The experimental results show that for H3L, compared with it in solution, the fluorescence intensity is enhanced as it is crystal and thin films, the fluorescence peak is red-shift, and the excited state lifetime is longer. The transition energies of the unimolecule is 240.2 kJ x mol(-1). For (n-Bu2)Sn(HL), the fluorescence intensity is stronger as it is crystal than it is in solution and the fluorescence peak is red-shilft, the excited state lifetime is longer. The fluorescence is quenched as it is in thin films. The transition energies of the unimolecule is 230.4 kJ x mol(-1). The fluorescence intensity of (n-Bu2)Sn(HL) is four times higher than the H3L. The excited state lifetime of (n-Bu2) Sn(HL) is longer than H2L too. In theory, these phenomena could be explained by that with the increase of the conjugated system and the rigid construction, the fluorescence intensity is stronger and the excited state lifetime is longer.