A novel bifat chain amphiphilic molecule nitrogencrown (NC) in Langmuir Blodgett (LB) films was characterized. The NC was adopted as an inert material for fabrication of optical nonlinear LB multilayers. The second harmonic generation (SHG) intensity increased quadratically with the bilayer number (up to 116 bilayers) in Y type hemicyanine (DAEP)/NC interleaving LB multilayers due to improvement of the structural properties by insertion of the long hydrophobic tail of DAEP molecules between two chains of NC molecules. The second order nonlinear susceptibility χ(2) ZXX (-2ω; ω, ω)=18 pM V -1 (or 4.4×10 -8 esu) was obtained by measuring SHG from the DAEP samples. The NC molecule has attractive features as a matrix material in fabrications of LB multilayers made from optically nonlinear molecules with hydrophobic long tails.