The disclosure provides a thermoelectric conversion structure and its use in heat dissipation device. The thermoelectric conversion structure includes a thermoelectric element, a first electrode and an electrically conductive heat-blocking layer. The thermoelectric element includes a first end and a second end opposite to each other. The first electrode is located at the first end of the thermoelectric element. The electrically conductive heat-blocking layer is between the thermoelectric element and the first electrode.