The dispersion stability of nanofluids is very important for the heat and mass transfer performance, therefore it is necessary to study and analyze influencing factors to the dispersion stability of nano-fluids. In this study, FeO-water and A12O3-water nano-fluids have been prepared, respectively. We analyzed a variety of influencing factors to the dispersion stability of the prepared nano-fluids, such as the dispersants' type, the mass proportion of the dispersant in base-liquid, the PH value of base-liquid, the ultrasonic power and the ultrasonic time. The optimum conditions of dispersion stability for preparation were explored through observing the sediment, measuring the absorbency, and...