A methacrylate copolymer, poly(MO), was prepared from radical copolymerization of octadecyl methacrylate and methacrylamide bearing DR-1 type azo-dye chromophore as NLO active group, which was synthesized through 7 reaction steps. Poly(MO) gave LB film on quartz substrate by the vertical dipping method. Transfer of the monolayer at the water-air interface was easier in upstroke than in down stroke. By SHG measurement for the multilayers it was found that only in the first monolayer exists an effective noncentrosymmetric structure of NLO chromophores, showing SHG. Unexpectedly, when a heat treatment was performed SH intensity of the monolayer decreased, whereas that of the multilayers increased significantly. More detailed investigations about this heat response behavior were carried out.