A single-knob air pump comprising a housing which is provided with a first air inlet/outlet and a second air inlet/outlet, wherein: an air extracting mechanism is arranged in the housing, and fan blades of the air extracting mechanism are arranged in a fan blade chamber provided with an air inlet and an air outlet; an air channel switching mechanism is arranged near the fan blade chamber and is provided with an air inlet and an air outlet; the air channel switching mechanism is operatively connected to a knob mechanism which can control the displacement of the air channel switching mechanism; and the second air inlet/outlet is provided with an air valve mechanism capable of closing or opening the second air inlet/outlet, and an ejector rod mechanism capable of closing or opening the second air inlet/outlet through the air valve mechanism under the action of the air channel switching mechanism is provided between the air valve mechanism and the air channel switching mechanism; so that when the air inlet of the air channel switching mechanism controlled by the knob mechanism is brought into contact with and is communicated with the air outlet of the fan blade chamber, the air outlet of the air channel switching mechanism is opposite to the second air inlet/outlet and the air channel switching mechanism drives the ejector rod mechanism to open the second inlet/outlet through the air valve mechanism, thus performing inflation; and when the air inlet of the air channel switching mechanism controlled by the knob mechanism is not communicated with the air outlet of the fan blade chamber, the air outlet of the air channel switching mechanism is opposite to the second air inlet/outlet and the air channel switching mechanism drives the ejector rod mechanism to open the second air inlet/outlet through the air valve mechanism, thus performing deflation; and when the knob mechanism controls the air channel switching mechanism to drive the ejector rod mechanism so as to make the air valve mechanism in a restored state, the air valve mechanism closes the second air inlet/outlet to stop working, characterized in that the air outlet of the air channel switching mechanism is provided with a V-shaped structure, including a first inclined plane and a second inclined plane; wherein in the inflated state, the first inclined plane abuts the ejector rod mechanism; in the deflated state, the second inclined plane abuts the ejector rod mechanism; and in a restored state, both the first inclined plane and the second inclined plane abut the ejector rod mechanism. an air extracting mechanism is arranged in the housing, and fan blades of the air extracting mechanism are arranged in a fan blade chamber provided with an air inlet and an air outlet; an air channel switching mechanism is arranged near the fan blade chamber and is provided with an air inlet and an air outlet; the air channel switching mechanism is operatively connected to a knob mechanism which can control the displacement of the air channel switching mechanism; and the second air inlet/outlet is provided with an air valve mechanism capable of closing or opening the second air inlet/outlet, and an ejector rod mechanism capable of closing or opening the second air inlet/outlet through the air valve mechanism under the action of the air channel switching mechanism is provided between the air valve mechanism and the air channel switching mechanism; so that when the air inlet of the air channel switching mechanism controlled by the knob mechanism is brought into contact with and is communicated with the air outlet of the fan blade chamber, the air outlet of the air channel switching mechanism is opposite to the second air inlet/outlet and the air channel switching mechanism drives the ejector rod mechanism to open the second inlet/outlet through the air valve mechanism, thus performing inflation; and when the air inlet of the air channel switching mechanism controlled by the knob mechanism is not communicated with the air outlet of the fan blade chamber, the air outlet of the air channel switching mechanism is opposite to the second air inlet/outlet and the air channel switching mechanism drives the ejector rod mechanism to open the second air inlet/outlet through the air valve mechanism, thus performing deflation; and when the knob mechanism controls the air channel switching mechanism to drive the ejector rod mechanism so as to make the air valve mechanism in a restored state, the air valve mechanism closes the second air inlet/outlet to stop working, characterized in that the air outlet of the air channel switching mechanism is provided with a V-shaped structure, including a first inclined plane and a second inclined plane; wherein in the inflated state, the first inclined plane abuts the ejector rod mechanism; in the deflated state, the second inclined plane abuts the ejector rod mechanism; and in a restored state, both the first inclined plane and the second inclined plane abut the ejector rod mechanism.