Abstract: In order to accurately analyze the factors affecting the temperature distribution of heavy oil reservoirs during high frequency electromagnetic heating, a mathematical model with dynamically varied reservoir properties was established based on the theories of electromagnetic field and heat transfer. In this model, frequency dependence of electrical conductivity and the relative permittivity of heavy oil reservoirs were taken into consideration, along with the temperature dependence of thermal conductivity and specific heat. In addition, COMSOL software of was employed to develop a mathematical model. Finally, the influencing laws governing temperature variation factors were studied by a contrast method. The calculations reflect a direct correlation between electromagnetic wave power and reservoir heating depth, and they demonstrate that the increase of electromagnetic wave power helps to increase the heating depth of reservoir. Although large electromagnetic wave frequency can lead to high temperature area nearby the wave source, the temperature value decreases sharply with the increase of depth. The results of a temperature calculation considering the dynamic change of reservoir properties differ from those calculated based on the constant reservoir properties. Reservoir temperature increases with the relative permittivity and conductivity within a certain range of variation. The results show that reservoir properties, electromagnetic wave power and frequency have a significant impact on temperature distribution of the reservoir and perhaps are prime influencers. The mathematical model that takes into consideration the dynamic change of reservoir properties provides a theoretical basis for the field application of a high frequency electromagnetic heavy oil heating technology.