Polydimethylsiloxane (PDMS) composite coatings filled with nanoparticles have been used extensively as anticorrosion materials. The alternating multilayer polydimethylsiloxane resin nanocomposite coating was first fabricated based on stepwise coating method via adding graphene and α-alumina. Their mechanical and anticorrosion properties were discussed. The binary fillers greatly improved the adhesion up to level 1, at the same time, the coating remained extreme flexibility. When the graphene was 0.3 wt%, the alternating multilayer coating exhibited the best corrosion resistance with the 4.82 V of corrosion potential (Ecorr), which was increased by near 40 times compared with pure PDMS coating. Meanwhile, the impedance value of composite coating reached 109 Ω•cm2. The corrosion current density (Icorr) of the coating was smaller than that of bare tinplate. The long-term soaking results prove that the alternating multilayer composite coating still possess the outstanding corrosion resistance for tinplate after 30 days of immersion.