Abstract: In view of the problems existing in the transformer water spray fire extinguishing system, the transformer water spray fire extinguishing system with fire extinguishing agent and the fire and explosion prevention capacity improvement scheme of the fire pipe network are proposed, and the application technology are expounded. A fire extinguishing test platform using a real 110 kV transformer model is built to study the influence of extinguishing agent on extinguishing transformer oil fire by water spray fire protection system. The results show that the pure water spray is difficult to extinguish the transformer oil fire in the area where the water spray is not directly injected or semi-covered. After adding fire extinguishing agent, simulated transformer fire can be extinguished within 42 s. After 16.7% of the sprayers are damaged, the water spray system with extinguishing agent could still extinguish the fire efficiently within 40 s. The test results provide reference for the construction of transformer water spray fire protection system.