<p>The preformed helical spacer significantly enhances the grip strength of spacer clamps and prevents conductor strand breakage, making it widely applicable in challenging environments such as Gobi regions and areas with large elevation differences. However, due to its substantial surface curvature, it is more susceptible to develop corona discharge compared to the common spacer, resulting in a more prominent corona discharge issue. It explores how the pitch, number of pitches, number of wires, and wire diameter of the preformed helical wires, as well as the conductor diameter, height, and distance between poles, influence the surface electric field strength. A rapid estimation method for evaluating surface electric field strength is proposed. Furthermore, an anti-corona discharge device is designed to effectively reduce surface electric field strength of the preformed helical spacer to levels below that of the conductor, thereby mitigating corona effects.</p>