Nuclear energy remains a key pillar in meeting energy demands and ensuring national security. Among the six candidates for Generation IV advanced reactors, molten salt reactors stand out for their innovative potential. The high-temperature molten salt pump, a critical component within the nuclear island of molten salt reactors, forms an integral part of the pressure boundary. Its safety and reliability are paramount to ensuring the stable operation of these reactors. Operating conditions present significant challenges: while the medium temperature inside the molten salt pump reaches up to 650 °C, the upper drive components require a lower-temperature environment for effective functioning. Therefore, it is essential to develop efficient thermal resistance techniques to minimize heat transfer upward and maintain a suitable working environment for the drive components. This study employs numerical simulations to analyze the thermal resistance properties of the molten salt pump's heat insulation screen. Key factors influencing the temperature rise in the upper portion of the pump are identified, and structural optimizations of the heat insulation screen are proposed and evaluated through structural mechanics analysis. The findings reveal that the thermal insulation material and the heat insulation screen's inner and outer ring frame structures significantly impact the temperature at the pump’s driving end. The optimized design not only effectively reduces the ambient temperature of the driving components but also satisfies structural mechanics requirements. These results provide a valuable reference for molten salt pumps’ structural design and thermal resistance analysis, ultimately enhancing their safety and service life.