The cationic Copolymers CQGP of Quaternary 4-vinylpyridine (QVPy) Graft N-vinylpyrrolidone PVP with varied molar ratios were synthesized by radical copolymerization in solution with 2, 2_azobisisobutyronitrile as an initiator. The process of the synthesis is based on two steps, first step vinylpyrrolidone (PVP) terminated 2- Hydroxyethylmethacrylate (HEMA) is produced by cationic polymerization using HClO4 as an initiator. The PVP product has different chain lengths of molecular weight average ranging 1500, 2000 and 3000 g/mol. The second step 4-vinyl pyridine was quaternized using Octyl bromide (C8Br), as quaternarizing reagent. The structure and composition of quaternary monomer, macromonomers and the copolymer were characterized by their FTIR, 1H NMR and ultraviolet spectra. The molecular weight was estimated by the technical viscosity using ethanol as solvent. The corrosion inhibition of Armco steel in 0.5 M sulfuric acid in the presence of cationic Copolymers CQGP of Quaternary 4-vinylpyridine (QVPy) Graft N-vinylpyrrolidone PVP was studied by weight loss measurement the results show that inhibition efficiency increases with the increase of concentration of inhibitor , and also we compared corrosion efficiency of each component of our copolymer separately PVP macromonomers and ploy(quaterny 4-vinylpyridine) by SEM the result showed that the PVP macromonomer hasn’t any corrosion inhibition properties and cationic copolymers possesses excellent corrosion inhibition.