Polyaniline (PANI) and its composites are applied to be promised protective coatings for corrosion control of steel materials. Electrodeposition of nano-composite made of silica dust nanoparticles (93.5% SiO2) and PANI on stainless steel surface from sulfuric acid solution was performed by cyclic voltammetry. The study was carried out using different techniques like, Fourier-transform infrared spectroscopy (FTIR), energy dispersive X-ray analysis (EDXA), X-ray powder diffraction (XRD), scanning electron microscope (SEM), thermal analysis, water sorption (WS) test and different electrochemical measurements. The silica nanoparticles decreased the electrodeposition rate, changed the structure, increased the thermal stability and decreased the water sorption of the PANI. The appropriate content of nanoparticles incorporated with PANI to produce highest protective layer was prepared from 0.04g silica/100 mL. Phosphate anions were doped of PANI molecules by aging the coated steels in phosphate solution. The coated SSs are spontaneously passive in 3.5% NaCl solution and they had lasted for a definite time before breakdown. More than three days phosphating of PANI- silica coatings kept the steel with no passivity breakdown (up to 350h). The formed under coating oxide film depends on the type of coating and plays important role for protection against pitting corrosion.