Abstract: A heat flux sensor, comprising: a ceramic heat sink; a sensitive element made of a single-crystal material and fixed to the ceramic heat sink through a thermally conductive and electrically insulative adhesive; a heat absorption layer arranged on an upper surface of the sensitive element; a first metal electrode and a second metal electrode arranged on the upper surface of the sensitive element; a third metal electrode arranged on the upper surface of the sensitive element; a fourth metal electrode arranged on a lower surface of the sensitive element; and a fifth metal electrode arranged on an upper surface of the ceramic heat sink; wherein a voltage signal between the first metal electrode and the second metal element is a transverse voltage Ux, and a voltage signal between the third metal electrode and the fourth metal electrode is a longitudinal voltage Uz.