Abstract: Regarding Xintan KD451 thick oil O/W emulsion, rheological property is studied based on the simulation of working condition. When water content is smaller than 80%, with middle-low shear rate, the O/W emulsion displays an obvious shear-thinning property; when water content achieves 80%, with shear rate surpassing 51s^-1, the O/W emulsion displays obvious Newtonian fluid characteristic. Under identical shear rate, the changeable appearance viscosity over time is mainly the result of the variation in emulsion's stability. The temperature, phase volume rate, mixture strength, oil and water nature, as well as drop's size and distribution have a strong impact on the flow property of the emulsion. Aiming at gathering characteristics of Xintan KD451 thick oil, a method for evaluating thick oil's O/W emulsion performance is proposed at the same time.