The waxy crude oil was routinely transported by means of adding pour point depressants (PPD), which can significantly improve the flow behavior of waxy crude oil. In this study, the physical properties of crude oil were first characterized. Subsequently, a novel variety of W/O nanoemulsion was prepared based on water in an EVA/toluene solution at a 3:1 proportion, and evaluated as a viscosity improver. It was found by virtue of the laser particle size analyzer that the EVA emulsion reaches the nano-scale. EVA nanoemulsion can present a behavior similar to nanocomposite PPD, and form a denser and regular structure with wax crystals via heterogeneous nucleation. Compared with conventional EVA, EVA nanoemulsion further reduces the oil viscosity, gel point and yield value by 52.8%, 0.05 °C and 29.6%. In addition, the impact of particle size of EVA nanoemulsion on the rheology of crude oil was discussed. In combination with DSC curve and POM, the action mechanism of EVA nanoemulsion on crude oil was analyzed.