This paper addresses the problem of material removal in electrorheological (ER) polishing with a mini annular integrated electrode both theoretically and experimentally. The model of the material removal profile in ER polishing is proposed based on the evaluation of the amount of material removed from the surface along the direction orthogonal to the tool path. Firstly, the electric field distribution around the tool head is deduced theoretically. On this basis, the contact pressure model in the ER polishing area is established. Considering the feed rate and tool spindle speed of ER polishing, the distribution of the relative sliding velocity in the polishing area is modeled. On the basis above, the innovative approach to calculate the material removal profile is developed for the ER tool polishing along a straight path. The model is validated by a series of designed polishing experiments, which demonstrates that the material removal model established in this paper has high prediction accuracy of material removal profile in ER polishing.