ITO-Al-ITO multi-layers were deposited at room temperature by RF magnetron sputtering on polyethylene terephthalate (PET). The films were deposited at various pressures of $8 imes10^{-4},;1 imes10^{-3},;4 imes10^{-3},;8 imes10^{-3};and;1 imes10^{-2}$ Torr. A correlation between microstructure and electro-optical properties was studied. Films deposited? at low pressure have higher transmission, and lower reflectance and resistance than film deposited at high pressure. Sheet resistance, transmission, and reflectance were $141.6Omega/Box;88\%;and;6.8\%$ resectively when the deposition pressure was $8 imes10^{-4}$ torr, that was the optimum condition.