SAGD (Steam Assisted Gravity Drainage) is used in Canadian fields where there are interlayers that impede steam chamber development and thus impede production. Many experiments have been conducted on the effect of interlayers on oil recovery. However, the swelling characteristics of interlayers under different conditions, as well as the possible clay mineral transformation and particle migration of clay particles at high temperatures, are rarely studied. In this paper, the swelling characteristics of natural oil sands and artificial clay samples were studied by high temperature hydration swelling experiments to obtain a better comparison. The effects of temperature, pressure and solution type on the swelling rate of oil sand were studied. The uniaxial compressive strength of the core in the presence of clay was studied by the scribe test. In addition, before and after the aging test at 220 °C and 2.5 MPa, the clay mineral composition was studied by the X-ray diffraction method, and the mineral transformation was proved. Finally, the impact of clay swelling on oil production is investigated by simulating the particle migration effect while considering the swelling effect. The results show that the swelling rate of oil sand increases with the increment of temperature and the decrement of pressure. The swelling rate of an artificial clay sample in distilled water is the highest, while a 1% KCl + 1% CaCl2 solution has the best swelling inhibition effect. This study aims to provide new insights into reservoir damage research during SAGD development.