Thermal stimulations of reservoirs cause significant amount of thermal energy stored subsurface and pore pressure altered from its original in-situ state. Such thermal and hydraulic disturbances inevitably stress and deform the rock formations including the reservoir and its overlying caprock, making the caprock integrity an important issue. This paper discusses the importance of thermally induced pore pressure for caprock integrity during a SAGD process. Relevant laboratory and field observations are presented to demonstrate its real existence, and then, numerical simulations are used to illustrate the major influencing material parameters and their evolving importance in space and time with respect to the steam chamber development. Finally, discussions are given about importance of the thermal pore pressure on the caprock integrity.