Aiming at the degradation of composite insulators caused by wind-sand erosion in ultra-high voltage grids extending to desert areas of Northwest China, this study investigates the evolution of surface roughness, hydrophobicity, and hydrophobicity transfer of silicone rubber composite samples under wind-sand conditions. Based on field-measured parameters from desert regions in Northwest China, a gas-solid jet erosion simulation system was established to test three types of silicone rubber samples by controlling erosion angles and durations. Key results indicate: Within the critical erosion angle range of 30°–60°, surface roughness peaks while hydrophobicity drops sharply. The high-hardness type exhibits a significantly higher increase in roughness than the high-tear-strength type. Although hydrophobicity deteriorates short-term, it recovers substantially after 1 h of resting. Dust accumulation demonstrates a dual-phase effect on hydrophobicity transfer: initial inhibition of migration followed by later normalization. Material performance comparison reveals optimal contact angle retention in the high-hardness type (132° ± 3° after 7 days), whereas the high-tear-strength type shows higher sensitivity to damage but a faster hydrophobicity transfer rate. This work provides a theoretical basis for insulator selection in high-intensity wind-sand regions.