In order to research the effect of temperature on oil-water relative permeability in the heavy oil reservoir，the heavy oil from a block in Venezuela was prepared as gas-bearing oil under simulated reservoir conditions. Oil-water relative permeability curves at different temperatures were determined through the unsteady-state method based on one-dimensional core flow simulation experiment. Research results show that the relative permeability of the heavy oil for the oilphase is high and very low for the water-phase，and the flow capacity between oil and water is extremely imbalanced. Along with the rise of temperature，the irreducible water saturation increases linearly and the residual oil saturation decreases nonlinearly，while the saturation corresponding to the equal-permeability point increases exponentially. The overall relative permeability curve shifts to right with increasing temperature. Furthermore，the imbibition area is enlarged and the oil and water relative permeability increases，but the rising amplitude of water was less than that of oil.