An air pump with automatic stop of inflation and deflation includes a housing provided with a first air inlet/outlet and a second air inlet/outlet. The inside of the housing is provided with a knob mechanism, an inflation and deflation linkage and an air channel switching mechanism which is connected to the product to be inflated or deflated through the second air inlet/outlet. The inflation and deflation linkage controls the air channel switching mechanism to be operatively connected to the knob mechanism which controls the displacement of the air channel switching mechanism so as to be communicated with the product to achieve inflation or deflation or not to be communicated with the product to achieve automatic stop of inflation or deflation.