The 35kV oil-immersed power transformer includes series such as S18, S20, and S22, with energy efficiency levels meeting the requirements of “GB20052-2024 Power Transformer Energy Efficiency Limits and Grades” for Level 3, Level 2, and Level 1. The transformer core is made of high-quality cold-rolled oriented silicon steel sheets with multi-level 45° fully slanted seam stacking, ensuring low losses. The coil can adopt a cylindrical or continuous coil structure, offering strong structural adaptability. The vacuum oil injection process enhances internal insulation performance, slows the aging of insulating oil, extends service life, and reduces partial discharge. The internal liquid can use mineral oil or environmentally friendly vegetable oil for insulation and cooling. The product is suitable for urban and rural grid upgrades, substations, and can meet special outdoor requirements in industries such as metallurgy and petrochemicals.