A power adapter, wherein the power adapter comprises: a housing, wherein the housing has an air inlet and an air outlet and the housing comprises a first surface and a second surface that are disposed opposite to each other; a circuit board component, wherein the circuit board component is located inside the housing; and a heat dissipation air duct, wherein the heat dissipation air duct is located in the housing, and wherein the heat dissipation air duct is a spacing area between the housing and the circuit board component, or the combination of the housing and a spacing area between the housing and the circuit board component, wherein the heat dissipation air duct surrounds the circuit board component and is connected to the air inlet and the air outlet, and the heat dissipation air duct is configured to dissipate heat from the housing, the circuit board component and the combination of the housing and the circuit board component, whereas the power adapter further comprises a first pin (20, 21) and a second pin (20, 22), characterized in that a first accommodation groove for accommodating the first pin (20, 21) and a second accommodation groove for accommodating the second pin (20, 22) are disposed on the first surface, and the first accommodation groove and the second accommodation groove are disposed at intervals; and the air inlet is disposed on a groove wall of the first accommodation groove, and the air outlet is disposed on a groove wall of the second accommodation groove or the air inlet is disposed on the second surface, the air outlet comprises a first sub-air outlet and a second sub-air outlet, the first sub-air outlet is disposed on a groove wall of the first accommodation groove, and the second sub-air outlet is disposed on a groove wall of the second accommodation groove. a housing, wherein the housing has an air inlet and an air outlet and the housing comprises a first surface and a second surface that are disposed opposite to each other; a circuit board component, wherein the circuit board component is located inside the housing; and a heat dissipation air duct, wherein the heat dissipation air duct is located in the housing, and wherein the heat dissipation air duct is a spacing area between the housing and the circuit board component, or the combination of the housing and a spacing area between the housing and the circuit board component, wherein the heat dissipation air duct surrounds the circuit board component and is connected to the air inlet and the air outlet, and the heat dissipation air duct is configured to dissipate heat from the housing, the circuit board component and the combination of the housing and the circuit board component, whereas the power adapter further comprises a first pin (20, 21) and a second pin (20, 22), characterized in that a first accommodation groove for accommodating the first pin (20, 21) and a second accommodation groove for accommodating the second pin (20, 22) are disposed on the first surface, and the first accommodation groove and the second accommodation groove are disposed at intervals; and the air inlet is disposed on a groove wall of the first accommodation groove, and the air outlet is disposed on a groove wall of the second accommodation groove or the air inlet is disposed on the second surface, the air outlet comprises a first sub-air outlet and a second sub-air outlet, the first sub-air outlet is disposed on a groove wall of the first accommodation groove, and the second sub-air outlet is disposed on a groove wall of the second accommodation groove.