The three-dimensional model is established with the numerical simulation software TOUGH2 of flow and heat migration, through a constant speed with long time of injecting fluids containing CO ₂ to simulate CO ₂ geological storage research on the effect of formation temperature. The results show that the formation temperature is in equilibrium before CO ₂ geological storage and the original balance is broken after sealing up. The higher the formation permeability is, the more conducive to the exchange of temperature. The temperature of whole formation undergoes the process from unsteady state to steady state, and because the exchange of formation temperature is restricted by the energy conservation, the final temperature of the whole formation is about at the initial time and the middle temperature of the lower formation temperature. The injected fluid continuously has a limited influence on the formation temperature, and the formation temperature changes rapidly in the early, the late change rate gradually slows down.