Special geological conditions such as oil and gas wells with CO₂ and CO₂ geological storage wells require high corrosion resistance of cement paste. In order to improve the corrosion resistance of cement paste，a waterborne resin without curing agent was selected as the anti-corrosion material. The improvement mechanism of corrosion resistance of cement paste by waterborne resin was analyzed. The results showed that the resin could effectively improve the corrosion resistance of cement paste. After 28 days of corrosion，the corrosion depth of cement paste with 15% waterborne resin was 68.7% lower than that of blank cement paste，meanwhile the compressive strength after corrosion was 12.8% lower than that without corrosion. The mixture of resin and cement slurry not only reduced the permeability of cement paste，but also reduced the large pore volume，therefore increased the corrosion flow resistance of CO₂ aqueous solution. The corrosion product formation of cement paste was reduced after resin was added into cement slurry. The microstructure of cement paste mixed with resin was denser. The film substance in cement paste increased the inertia of corrosion reaction. The waterborne resin without curing agent could improve the corrosion resistance of cement paste by reducing the formation of alkaline hydration product，increasing the penetration resistance to acid fluid and enhancing the inertia of corrosion reaction.