The invention relates to a temperature image sensor and a preparation method thereof. The temperature image sensor comprises a readout circuit chip, a memory chip and a temperature sensing chip whichcomprises at least one sensing pixel unit; the readout circuit chip includes a first surface and a second surface opposite to each other; the memory chip is bonded to the first surface of the readoutcircuit chip by a first bonding layer; and the temperature sensing chip is bonded to the second surface of the readout circuit chip through a second bonding layer. The memory chip and the readout circuit chip are bonded through the first bonding layer; the temperature sensing chip and the readout circuit chip are bonded through the second bonding layer; and therefore, the preparation process of the temperature image sensor is simplified, preparation cost is reduced, the mass production of the temperature image sensor is facilitated, the area of the temperature image sensor is reduced on the premise of ensuring the function of the temperature image sensor, and the miniaturization of the temperature image sensor is realized.