Abstract: The vibration of the electrode wire represents a significant factor influencing the precision of large taper EDM wire cutting. In order to enhance the precision of the machining process, a device that can compensate for the movement errors of the electrode wire in real time has been designed. On this basis, the key factors affecting the evaluation index and the influence law are explored through single-factor experiments. The influence of each parameter combination on the evaluation index is derived through 16 groups of orthogonal tests, comprising four factors and four levels each. The Taguchi method was employed to ascertain the relative importance of each factor, while the grey relation analysis was used to optimise the evaluation indexes in a multi-objective framework. The results demonstrate that the quality of workpiece processing is enhanced when the pulse width is 2 μs, the pulse gap is 4 μs, the number of amplifiers is 2, and the wire speed is 3 m/s. The optimised parameters were employed for the machining of workpieces. Following an experimental comparison, it was observed that machining with the optimised parameters resulted in a reduction of the total workpiece size error by 47.80%, the total average surface roughness by 31.09%, and the total average cutting speed by 13.80%. A new follower wire guide structure has been proposed to optimize EDM wire cutting machining accuracy.