High frequency thermoacoustically‐driven pulse tube cryocoolers are quite promising due to their compact size and high reliability, which can find applications in space use. With continuous effort, a lowest cold head temperature of 68.3 K has been obtained on a 300 Hz pulse tube cryocooler driven by a standing‐wave thermoacoustic heat engine with 4.0 MPa helium gas and 750 W heat input. To further reduce the size of the system, a coaxial resonator was designed and the two sub‐systems, i.e., the pulse tube cryocooler and the standing‐wave thermoacoustic heat engine were properly coupled through an acoustic amplifier tube, which leads to a system axial length of only about 0.7 m. The performance of the system with the coaxial resonator was tested, and shows moderate degradation compared to that with the in‐line resonator, which might be attributed to the large flow loss of the 180 degree corner.