Two Schiff bases with different alkyl chains length, N-dodecyl (2-hydroxy-5-nitro-benzylideneaminato) (TA12) and N-hexadecyl (2-hydroxy-5-nitro-benzylideneaminato) (TA16), were synthesized. Their monolayers behavior and LB films characteristics were investigated and compared by pi-A isotherm, UV-Vis absorption spectra, fluorescence spectra and Micro-IR spectra. The results indicate that TA12 and TA16 have good formation properties. J-aggregate was found in LB films of Schiff bases that have photoluminesence properties. The Schiff base with longer alkyl chains is more orderly in LB films. But the whole films are not so perfect in microscopic state.