ing at the problems of thermal effect accumulation and iterative processing efficiency in the process of off-axis parabolic mirror ion beam modification, a method is proposed to combine batch machining with variable beam diameter machining, which divided the total removal amount according to a certain proportion, and the experimental exploration is carried out by using this method. The spherical mirrors with an aperture of 110 mm, a radius of curvature of 1732.7 mm, an initial surface peak-valley value (PV) of 0.525λ (λ=632.8 nm) and a root mean square (RMS) value of 0.025λ are polished in batches. The off-axis parabolic mirrors with vertex radius of curvature of 1728 mm, off-axis of 85 mm, PV of 0.36λ and RMS of 0.029λ are obtained. Based on the analysis of the experimental process and results, it is proved that the batch machining method can effectively eliminate the thermal effect in the ion beam machining process, and the local finishing method with variable beam diameter can reduce the number of iterative machining and improve the machining efficiency.