Submicron-sheet zinc phosphate (SZP) was synthesised by sol–gel method. Anticorrosion behaviour of epoxy coating with SZP was investigated by electrochemical impedance spectroscopy, gravimetric test, adhesion test and scanning electron microscopy. Results showed that the submicron-sheet structure of SZP pigment can reduce defects in the coating, improve consistency of pigment/resin interface and lengthen diffusion pathways. SZP pigments in coating had more contact area with permeating water, ensuring PO₄³⁻ quickly attained the specific density to inhibit corrosion on the steel surface. Thus, SZP pigment can enhance the barrier properties of coatings and effectively inhibit the corrosion reactions at coating/metal interface.