After the injection of nano-silica (nano-SiO₂) into the reservoir, the acid corrosion of CO₂ on reservoir rocks can be effectively avoided, ensuring the safety of CO₂ storage. However, accurate prediction of the temperature distribution in nano-SiO₂-CO₂(nano-SiO₂ synergistic CO₂ mixed fluid) injection wells is currently not achievable in existing research, which makes it difficult to precisely control the formation temperature after nano-SiO₂-CO₂ injection, thereby impacting the safety of storage. A temperature distribution prediction model for nano-SiO₂-CO₂ injection wells, considering the gas-liquid-solid ratio distribution, was established based on mass conservation and energy conservation principles. Furthermore, through the nano-SiO₂-CO₂ injection pipeline friction experiment, a model for calculating the wellbore friction factor of nano-SiO₂-CO₂ mixed fluids under supercritical conditions and different flow regimes was proposed. This model enabled accurate prediction of the temperature distribution in nano-SiO₂-CO₂ injection wells. The field well temperature distribution calculation results show that the temperature prediction error is less than 1%, verifying the reliability of the model. Finally, through numerical simulation analysis of nano-SiO₂-CO₂ injection well temperatures, the impact laws of various parameters on the temperature distribution were clarified, providing theoretical support for optimizing nano-SiO₂-CO₂ injection parameters, thereby improving the injection efficiency and ensuring the safety of CO₂ storage.