This invention relates to a method of preparing anti-corrosive hybrid sol-gel film coating on zinc or zinc alloy coated metallic substrates comprising the steps of preparing a mixture of sol-gel from hydrolisable silicon alkoxides, sodium venadate solution combined with colloidal silica in a beaker and vigorously stirred; adding within 20 seconds of two separated phase formation between silica precursors and colloidal silica acetic acid or dilute nitric acid as a catalizer to initiate hydrolysis reaction of silicon alkoxides and condensation reaction in the sol gel composition, continuously stirring the mixture for about 24 hours to form a single phase solution, applying the solution on cleaned zinc or zinc alloy coated metal substrates to form a transparent sol-gel coating film and drying the coated substrates at 50° to 200° C. for 10 to 60 minutes.