Abstract: Focused on poor thermal stability and narrow processing window of CPVC resin serving as matrix material for high-voltage cable laying CPVC protective sleeves, the formulation of sleeves was designed and optimized under established processing technology to improve product quality. Results showed that the calcium-zinc composite stabilizer at 4.5% mass fraction and calcium stearate at 1.1% mass fraction effectively enhanced thermal stability, improved surface appearance, and increased impact resistance. The composite system of 0.8% mass fraction internal lubricant and 1.2% mass fraction external lubricant improved processing fluidity of the blend and enhanced ring-section compressive strength of sleeves under thermal compression conditions. Synergistic toughening with 6.0% mass fraction methyl methacrylate-butadiene-styrene (MBS) and 3.0% mass fraction chlorinated polyethylene (CPE) achieved maximum notched impact strength of sleeves. The addition of 1.8% mass fraction acrylic ester copolymer (ACR) impact modifier facilitated plasticization of the blend and improved surface quality of sleeves. Furthermore, 15.0% mass fraction activated calcium carbonate was used as filler to maintain the performance of sleeves while reducing production costs. Finally, including 16.0% mass fraction polyvinyl chloride (PVC) resin met the standard requirement of Vicat softening temperature of sleeves above 93 °C and further reduced raw material costs. This research and analysis can provide a reference for formulation optimization of CPVC protective sleeves.