The　propagation　properties　of　stress　waves　in　rock　masses　are　of　great　importance　for　exploring　the　internal　structure　of　the　Earth　and　avoiding　earthquake　disasters.　Based　on　the　modified　displacement　discontinuity　method,　the　non-attenuation　behavior　of　stress　wave　propagation　through　a　rock　mass　with　a　large　wave　impedance　to　a　rock　mass　with　a　small　wave　impedance　was　studied.　The　results　show　that　the　non-attenuation　propagation　of　stress　waves　can　occur　when　stress　waves　propagate　from　rock　with　a　large　wave　impedance　to　rock　with　a　small　wave　impedance.　The　non-attenuation　propagation　of　stress　waves　is　related　to　the　incident　wave　frequency,　the　joint　stiffness　and　the　wave　impedance　ratio.　The　non-attenuation　propagation　of　stress　waves　is　most　likely　to　occur　when　the　incident　wave　frequency　is　low　and　the　joint　stiffness　and　wave　impedance　ratio　are　large.　According　to　the　critical　condition　for　the　non-attenuation　propagation　of　stress　waves,　a　threshold　surface　was　identified.　The　region　corresponding　to　non-attenuation　stress　wave　propagation　exists　below　the　threshold　surface.