In order to further understand the Vacuum arc remelting(VAR) process, with the help of OpenFOAM, an open source CFD computing software, a two-dimensional multi-physical finite volume model (FVM) including electromagnetic field, temperature field and flow field was established to study the macroscopic phenomenon of the unsteady solidification process on GH4698 nickel-based super alloy ingots. Results shows that magnetic induction intensity induced by the current flowing from the crucible to the consumable electrode is mainly concentrated on the upper part of the ingot and rotates along the axis of the ingot. The magnetic induction intensity first increases and then decreases from the center to the edge of the ingot, and reaches the maximum value at the edge of the electrode. Thermal buoyancy and lorentz forces are the main driving forces in the molten pool and their effect on the flow of molten pool is opposite to each other.