Under high temperature and high-pressure water-containing gas-phase CO₂ environments，conventional silicate cements are susceptible to corrosion by acidic environments，which results in strength decline and structural deterioration. Mixing nano-SiO₂ in cement can reduce the Ca/Si ratio and permeability，thus improving the material's resistance to high temperature and corrosion. Nano-silica particles（NS）and sol-gel（SS）as the most common types of nano-SiO₂，but the application of the two materials in the cement paste has its own advantages and disadvantages. In this paper，based on the high-temperature and high-pressure vapor-phase CO₂ corrosion experiments，the compressive strength，XRD，FTIR and SEM tests were carried out to investigate the influence laws of different types of nano-SiO₂ on the mechanical strength，types of corrosion products and hydration products，and microstructures of the cement stone. The results showed that the compressive strength of cementite increased by 1.82%，9.1% and 15% sequentially at 150 ℃ with 1%，2% and 3% NS，while it decreased by 7.73%，4.09% and 2.73% with 1%，2% and 3% SS，respectively. Compared to the oil well cement，the Ca/Si ratio of C-S-H gel in the hydration product was reduced by 33.23% and 24.37%，and the Ca（OH）₂ content was reduced after mixing 3% NS and 3% SS，respectively. The addition of NS made the diffraction peak intensity of the hydration product Ca（OH）₂（001）crystal plane decrease obviously，and improved the crystal orientation of Ca （OH）2. The decline rate of the cement compressive strength was reduced by 10.35 percentage point and 10.98 percentage point，and the corrosion products CaCO₃ were reduced，the cement particles were more strongly cemented，and the corrosion resistance of cement stone was improved. Comprehensive comparing the mechanical strength and microstructure of cement stone before and after corrosion，NS had better effect on improving the high temperature resistance and corrosion resistance of cement stone than SS.