The surface temperature of a ballistic missile in flight is a key point concerned by both the missile attacking side and the missile defense side. The surface temperature and infrared radiation source of ballistic missiles in their boost phases, middle phases and re-entry phases are reviewed. The equilibrium temperature of the warhead and decoy of the ballistic missiles in middle phases are given mainly. The warhead nearly keeps its initial temperature because of higher thermal inertia, whereas the balloon decoy reaches its equilibrium temperature quickly because of lower thermal inertia. Finally, that the dynamic thermal radiation measurement in actual flight tests is the important direction of surface temperature theory study is pointed out.