Existing experimental and theoretical studies have identified the existence of an electric field in wind-blown sand, whose strength is hundreds to thousands of times larger than that of the fair-weather electric field (around 120v m− 1) and is related to the intensity of the wind-blown sand transport. The direction of electric field is often upward pointing and opposite to that of the fair-weather electric field. In this study, we performed theoretical predictions of electric fields in wind-blown sand transport by assuming a constant charge-to-mass ratio (i.e., − 60µc kg− 1) of the saltating particles and considering the streamwise spatial variation of particle concentration in the evolution of wind-blown sand. Our results show that there exist both vertical and horizontal electric fields in wind-blown sand transport. The numerical results of vertical electric fields and mass flux are in good agreement with the experimental data measured by Schmidt et al.  and Shao and Raupach , respectively, which suggests that our model is valid. The horizontal electric field demonstrates a vertical stratification feature and is about one order of magnitude bigger than the fair-weather electric field. Finally, the effects of the wind speed and the sand grain diameter on electric fields are discussed.