Pressure oscillating tubes are core components of the gas wave refrigerator. The reverse compression waves will limit refrigeration efficiency by reheat cooling gas. The promotion from traditional rotation gas wave refrigerator with single opened pressure oscillating tubes to the streamlined pressure exchange gas wave refrigerator with double opened pressure oscillating tubes is mainly in terms of this issue. However, through weakened, reverse compression waves are still inevitable. For further development, the concept of a wave attenuator has been proposed, installed at the high-temperature (HT) port. Numerical simulation has been utilized to analyze mechanism of wave attenuator and the practical effect has been proved by experiment research. The conclusions are as follows: due to structure of wave attenuator, the intensity of reverse compression waves has been weakened; the optimal structure of wave attenuator has been obtained; the refrigeration efficiency of the refrigerator has been significantly increased because of wave attenuator in HT port.