The 35kV series oil-immersed power transformers are advanced in design and have been greatly improved in material, structure and technology. High and low pressure clamps adopt steel belt or upper beam and side beam to tighten, forming a solid frame structure and enhancing the iron core clamping force and resistance to transport impact. Strong resistance to short circuit, beautiful appearance, reliable operation, low loss, low noise, advanced level of similar foreign products. The sz11-8000/35 transformer prototype manufactured by our company has passed the sudden short circuit test conducted by the national transformer testing center once and for all. The vertical oil duct set by the high and low voltage coils is conducive to heat dissipation and can greatly reduce the temperature difference of copper oil and the most hot spot temperature rise inside the coils.