Stearoyl chloride was used for amidation modification reaction of melamine to obtain the melamine derivative modified by octadecyl chain, which was then added and polycondensation reaction with formaldehyde to prepare stearoyl modified dense amine resin, which was respectively applied in the preparation of film formation and foaming materials. The structure and properties of stearoacylated melamine, its modified melamine resin, film and rigid cellular material were compared and analyzed. The results showed that the contact Angle of stearoacylated melamine increased from 0° to more than 136° due to the introduction of hydrophobic alkyl chain. And in the reaction of hydrophobic modified melamine resin, melamine as stearic acylation degree enhancement, the water of the hydrophobic modified melamine resin stand point temperature decreases gradually, resin viscosity increases gradually, insoluble particles increase gradually increased, and the appropriate by stearic acid chloride modified reaction of melamine, the preparation of acylation melamine material, coating materials and rigid cellular material, For example, the compressive strength of the sample can reach 39.5MPa, the bending strength of the rigid cellular material can reach 345.8kPa, and the compressive strength can reach 315kPa. At the same time, the water absorption of the acylated sample can be reduced from 4.5% to 1.1%. The water contact Angle was increased from 68.5° to 107.5°, and the stain resistance was further improved. The volumetric water absorption of the rigid cellular material was reduced from 5.2% to 2.0%.