To improve the computational accuracy of water-droplet collision coefficients and ice accretion growth in icing predictions for DC transmission conductors, a multiphysics numerical model incorporating the effects of a DC electric field was established. Within the Euler–Lagrange framework, the Magnetohydrodynamics (MHD) module in FLUENT was employed to calculate the DC electric field around the conductor, while the Messinger thermodynamic model was coupled to determine the local collision coefficient, ice accretion mass, and ice shape. Unlike conventional static simulation methods, the proposed method updates the computational boundaries and mesh according to the ice shape generated at each icing time step and recalculates the flow and electric fields, thereby enabling iterative simulation of the icing process. The collision coefficients predicted by the model were in good agreement with the experimental results, and the predicted ice shapes exhibited trends broadly consistent with existing experimental observations. Based on this model, the trajectories of charged droplets in the flow field around the conductor were simulated, and the effects of electric field intensity, droplet volumetric charge density, and median volume diameter on the conductor collision coefficient and ice accretion characteristics were investigated. The results showed that increasing the DC electric field intensity weakened the droplet-capturing capability near the windward stagnation point, causing both the local collision coefficient and ice accretion mass on the conductor surface to decrease with increasing electric field intensity. When the electric field intensity increased from 0 to 25 kV/cm, the collision coefficient of droplets with a diameter of 77.7 μm decreased by nearly 30%. As the droplet volumetric charge density increased, the total ice accretion decreased significantly, accompanied by a simultaneous reduction in the icing area. When the droplet volumetric charge density reached 0.12 C/m³, the ice accretion mass per unit length of the conductor was reduced by nearly 70% compared with that under the uncharged condition of 0 C/m³.