<p>The high-volume-fraction SiC particle-reinforced aluminum matrix composites (SiCp/Al) machined by high-speed wire electrical discharge machining (HS-WEDM) can only cut under low energy, and it is easy to break the wire when cutting under high energy. The causes of the problem are analyzed. According to the analysis, it is considered that when cutting SiCp/Al composites, the presence of aluminum oxide and silicon dioxide insulating particles on the wire electrode surface leads to a gap discharge state between the wire electrode and the conductive block. Additionally, the contact angle between the wire electrode and the conductive block is small, resulting in unstable sliding contact. With an increase in discharge energy, the high-speed and vibrating wire electrode becomes susceptible to wire breakage. To address this problem, an open-guide-wheel power supply method is proposed. This method increases the contact area and angle between the wire electrode and the guide wheel, achieving a stable power supply through rolling contact and effectively suppressing the electric corrosion effect. Additionally, the open structure resolves the issue of the power supply device burning out, which occurs with the traditional closed structure. The experimental results show that using the open-guide-wheel power supply method achieves persistent and efficient cutting of 70-mm 55vol.% SiCp/Al composites. The cutting efficiency is 111.65 mm²/min, which is more than three times the long-term cutting efficiency of the conductive block power supply method.</p>