Abstract: To address the issues of non-degradable insulation materials and insufficient stability of pressure balance devices in traditional normal-pressure sealed air-insulated switchgear, this paper develops an integrated insulation support base and symmetrical insulation sleeve using degradable thermoplastic composite material(PC+glass fiber). This achieves a 30% increase in injection molding efficiency, 50% weight reduction of insulation components, and 10% reduction in circuit breaker parts. Simultaneously, a novel pressure balance device based on expanded polytetrafluoroethylene(ePTFE) waterproof breathable membrane is developed, effectively isolating moisture and contaminants in the gas chamber. Finally, through electric field simulation and experimental verification, the proposed solution meets insulation requirements under atmospheric pressure, providing technical support for environmental sustainability and performance optimization of normal-pressure sealed air-insulated switchgear.