The invention discloses a combined protective circuit of a thermosensitive head piece, which comprises a CPU, a power supply port connected to the thermosensitive head piece, and a power supply control circuit used for controlling power on/off of the thermosensitive head piece. In order to realize the multiple protection of the thermosensitive head piece, a programmable logic unit is also connected to a total output effective control port of the thermosensitive head piece, a frequency division timing/counting device is configured in the programmable logic unit, when the counting of the frequency timing/counting device reaches a set value, the programmable logic unit outputs an invalid level to the total output effective control port of the thermosensitive head piece for controlling the thermosensitive head piece to stop heating when not receiving an emptying or presetting command sent by the CPU. The thermosensitive head piece is controlled by adopting a combined protective measure, thus the damage of the thermosensitive head piece when the system program is out of control or part hardware is damaged can be prevented, and a thermosensitive printer is effectively protected.