Lattice Boltzmann method (LBM) is used in a coupled perfect dielectric model and liquid-vapor phase-change model to simulate nucleation, growth, and separation process of a single bubble in pool boiling under uniform electric field. Effects of gravitational acceleration and electric field on bubble dynamics are studied in detail. It shows that under same gravitational acceleration, with the increase of electric field intensity, the bubble departure diameter decreases and the bubble release frequency increases, and the averaged wall heat flux increases. With the decrease of gravitational acceleration, the averaged wall heat flux decreases as well, and the electric field has significant influence on the bubble release frequency. In addition, the bubble deforms in a uniform electric field, and it stretches along the direction of electric field to become slender. The electric field intensity is linearly related to the aspect ratio and height of the bubble.