The valve hall of the converter station is the core area of the direct current equipment. The fireproof performance of the valve hall blockage plays an important role in supporting the daily operation of the direct current transmission system. This paper analyzed the fire protection capability of the plugging structure of the high-end valve hall in±1 100 kV UHV converter station. This paper determined the fire hazard source according to the material and working mechanism of the blocking structure of the±1 100 kV high-level valve hall. This paper established a blocking physical simulation model of the±1 100 kV valve hall, and simplified it according to the blocking structure components. The t² fire source model was used to describe the heat release rate of the fire hazard source. The temperature variation trend and the fire spread of the valve side casing when the valve side was on fire were calculated through the visual operation software PyroSim. The simulation results show that the fire spread is limited to the valve side casing area, indicating that the high-end valve hall plugging structure can inhibit the spread of the fire, which provides key basis for designing a reasonable fire extinguishing plan.