During thermal oil production, the thermal conductivity is very complex, so experiments were conducted in the reservoir temperature and reservoir pressure. The effects of reservoir pressure, porosity, water saturation on thermal conductivity of rock were analyzed, and the characteristics of thermal conductivity of reservoir were discussed. The results showed that the determinant for thermal conductivity of reservoir rock is porosity and water saturation. According to the experiments, experiential formulae for thermal conductivity of reservoir are proposed. During thermal oil production, the mechanisms of thermal conduction are controlled by the system of rock-oil-water. The bigger the conductivity is, the quicker the thermal conducts, and the higher the thermal efficiency is.