本論文探討在線性區間，單顆量子點連接金屬電極再接外部負載時系統轉換效率。利用格林函數求得電流與熱流，並推算出電導、熱導、席貝克係數與熱電優值( ZT )，最後得到轉換效率。在改變冷端溫度時系統轉換效率下降，而改變兩端溫差則使效率上升。同時，發現熱電優值越大，則轉換效率則以兩端溫差決定，類似卡諾引擎。除此之外，聲子熱導會明顯的抑制效率大小，因此降低聲子熱導是非常重要的議題。最後，我們討論外部電導對轉換效率的影響。我們發現當系統本身電導與外部電導的比值越靠近√(1+ZT)，則系統轉換效率為最大。;In linear response regime, we study the efficiency of a single quantum dot (QD) embedded into a matrix connected to two metallic electrodes with a temperature difference. The electrical conductance, thermal conductance, Seebeck coefficient, figure of merit (ZT) and the efficiency (η) of QD junction system are calculated from electron and heat currents which are derived by the Green’s function technique. η is enhanced by increasing a temperature bias at a fixed cold-side temperature, but it is suppressed by increasing a cold-side temperature at a fixed temperature bias. Meanwhile, the behavior of system is similar to a Carnot engine when ZT is infinite. Finally, we have investigated how the η is influenced by the external conductance. The maximum value of η occurs when the ratio between the electrical conductance and external conductance equals to √(1+ZT).