Abstract The modified waterborne acrylic resin was synthesized successfully by emulsion polymerization with octafluoropentyl methacrylate and phosphate functional monomer as monomers, showing an improved anti‐corrosion performance of the resin coating. The existence and general distribution of the elements of the modified monomer in the emulsion were explored, and the anti‐corrosion mechanism was disclosed. The results show that the modification of octafluoropentyl methacrylate and phosphate functional monomers improved the water resistance, corrosion resistance and thermal stability of acrylic resins. Compared with unmodified acrylic resin, the contact angle of the modified resin was increased from 74.23° to 83.51°, and the initial decomposition temperature was increased from 264 to 305 °C. At the same time, the corrosion voltage of the modified resin was increased, the corrosion current density was decreased, and the salt spray resistance was improved. This study provides a new way for the preparation of environmentally friendly, stable, and corrosion‐resistant waterborne acrylic resins.