to enhance the thermal conductivity of via hole in PCB of electrical power units,a formula was deduced to calcu-late the thermal conductivity of via hole. This formula was verified by both numerical simulation and experiment. With the formu-la,the impacts of via hole diameter,filling material and copper plating thickness on thermal conductivity are studied in this pa-per. The conclusions are that via hole diameter of 0.45 mm is the best value;FR4 or Rogers;filling material of the via hole can get minor benefit on thermal conductivity,but if filling with high conductivity material such as solder,the thermal conductivity is improved obviously;the plating layer thickness of via hole impacts the thermal conductivity most,which appears a liner growth relationship between the thickness and the conductivity. With the three recommend optimization methods,the thermal conductivity of via hole can increase by 6.5%,35% and 51% respectively.%为了对电源设备的印刷电路板（PCB）散热过孔的导热性能做优化提高，推导了一套理论计算公式，采用数值仿真、实验测试的方法验证了该公式的可靠性。通过该理论计算公式，研究了散热过孔的孔径、填充的材料以及过孔镀铜厚度对导热率的影响。研究结果显示，过孔内孔直径为0.45 mm为最优直径；填充材料为FR4或者Rogers时没有明显的改善，但是如果用焊锡等高导热率的材质填充时导热率有明显的提高；过孔镀层厚度对导热率的影响非常大，呈线性的增长关系。采用该结果推荐的三种散热过孔优化方案，能使导热率分别提高6.5%，35%及51%。
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