In order to ensure thermal reliability and adaptability to temperature change of the internal electronic components and equipment with multi functional structure, the thermal analysis module was used in ANSYS software to make the analysis of heat conduction and thermal stress analysis for RTU of prototype with multi functional structure used on cartridge, and the rationality of the structure design was verified, which laying the design foundation for thermal design of electronic equipment in theory. Through research on prototypes about circulation experiment in power and the temperature burn in test, it is known that the prototype works steadily and the structural design is reasonable.