A new concept of pulse tube refrigerator using gap regenerator as its regenerator is suggested.The physical model of this pulse tube refrigerator is established.The influences of frequency,gap width,opening of orifice and double inlet valves on the refrigerator performance have been analyzed by numerical calculation based on the finite difference method.It shows that in the pulse tube refrigerator with a gap regenerator, the optimum frequency,optimum openings of orifice and double inlet valves are less than those of the pulse tube refrigerator with screen-matrix regenerator.