A touch sensing device and 2D sensing information update method used therein is disclosed. Before updating the 2D sensing information for use as a reference 2D sensing information, the processor determines the touch sensing panel is under an abnormal condition if any flatness index is smaller than a predetermined flatness index negative reference value or larger than a predetermined flatness index positive reference value, and will then keep measuring the capacitive coupling amount at each sensing point and getting respective flatness indexes, and will then update the 2D sensing information for use as a reference 2D sensing information when all the flatness indexes are in the range between the predetermined flatness index negative reference value and the predetermined flatness index positive reference value.