This study studies the effect of flow and thermal transfer properties of fluids with varying densities, viscosities, and thermal conductivities on the performance of oil shale in-situ conversion process based on multi-physics coupling simulation. Results indicate that thermal convection primarily governs the heat transfer pro­cess in oil shale. Consequently, to enhance the pyrolytic effects, fluids possessing high density, low viscosity and superior thermal conductivity are recommended. This research thus provides a foundational understanding for the selection of fluid properties in the in-situ extraction of oil shale.