A package structure is provided. The package structure includes a semiconductor die and a thermoelectric structure disposed on the semiconductor die. The thermoelectric structure includes P-type semiconductor blocks, N-type semiconductor blocks and metal pads. The P-type semiconductor blocks and the N-type semiconductor blocks are arranged in alternation with the metal pads connecting the P-type semiconductor blocks and the N-type semiconductor blocks. When a current flowing through one of the N-type semiconductor block, one of the metal pad, and one of the P-type semiconductor block in order, the metal pad between the N-type semiconductor block and the P-type semiconductor block forms a cold junction which absorbs heat generated by the semiconductor die.