Al(OH)(3) thin films were assembled on anionic polysulfonamide (PSA) fabrics by electrostatic self-assembly method to improve the mechanical, heat insulation, and flame retardant properties of PSA fabrics. PSA fabric surface was modified with a chemical reaction to build-up anionic charge known as anionization. Then a homogeneous Al(OH)3 film was deposited in the fiber interstices after the treatment of Al(OH)(3) nanoparticles by electrostatic self-assemblies. The scanning electron microscopy (SEM) and X-ray powder diffraction (XRPD) were used to verify the presence of deposited Al(OH)(3) thin films. Tensile strength, heat insulation, and flame retardancy of PSA fabrics were analyzed before and after the treatment of Al(OH)(3) thin films. It was proved that the heat insulation and flame retardancy of PSA fabrics could be improved by Al(OH)(3) films additive through electrostatic self-assembly process.