Abstract: Spacecraft is a complete machine of electronic products,astrospace is used as heat sink. Discharging heat out to external space effectively is the primary mission of spacecraft thermal design. But for electronic products inboard, the mission is mainly transmitting thermal power dissipation to baseplate,enclosure and bulkhead,make sure that components work reliably in the range of allowable working temperature. Apply finite element analysis software FloTHERM to conduct thermal analysis during spacecraft electronic products design period,adjust and optimize the thermal control scheme to make electronic components work safely and reliably.