A numerical study on the electrokinetic motion of a charged oil droplet near a charged air-water interface is presented in this paper. First, the separation distance between the oil droplet and the air-water interface is calculated, and then the electrokinetic velocity of the droplet is simulated utilizing a three-dimensional numerical model under different applied electric fields, droplet's radii, ionic concentrations, zeta potentials of the oil-water interface, and zeta potentials of the air-water interface. The numerical results indicate that a negatively charged oil droplet near a negatively charged air-water interface moves in opposite direction of the direct current electric field and has larger velocity under higher electric field strength, droplet's radius, ionic concentration, and absolute values of the two interface zeta potentials. (C) 2018 Elsevier Ltd. All rights reserved.