An air chamber structure for a medical air compressor, the chamber being provided between the pump and an air bed. Two flow guiding stubs are provided at an air input end to scatter air and render it to revolve in a storage chamber with a smaller space, the air is led into a larger pressure stabilizing chamber through a flow guiding port during continuous pumping of air into the storage chamber, and hence the output of the air can be stable and at a constant flow rate. An air output pipe is located on one edge opposite to the storage chamber, and air is uniformly spread in the pressure stabilizing chamber, and is put out from the output pipe at a constant flow rate, thus avoiding the disadvantage of generating resonance and wind noise in the inflated bed.