The irreversible and reversible thermosensitive (heat) ink coloring principle is summmarized. The temperature indicating function of the irreversible thermosensitive (heat) ink is expounded in the fields of food and medicine packaging while the application of reversible thermosensitive (heat) ink in packaging anti-counterfeiting is analyzed as well. The development direction of thermosensitive (heat) ink is prospected as developing the thermal (heat) ink for offset and gravure printing which is of low cost and high color sensitivity for temoerature.