This　paper　investigates　the　effects　of　the　gradient　distribution　of　microdefects　on　wave　propagation　through　a　rock　mass.　A　piecewise　three-characteristic　lines　method　is　proposed　that　can　consider　the　gradient　distribution　of　microdefects.　A　rock　mass　with　a　microdefect　gradient　distribution　was　explored　and　compared　to　wave　propagation　through　a　rock　mass　with　a　uniform　distribution　of　microdefects.　Subsequently,　the　effects　of　gradient　and　frequency　on　the　particle　stress　transmission　coefficient,　particle　velocity　transmission　coefficient,　and　energy　transmission　coefficient　were　discussed.　The　results　indicate　that　a　rock　mass　with　a　microdefect　gradient　distribution　significantly　affects　wave　propagation.　The　traditional　study　of　wave　propagation　in　a　rock　mass　with　a　uniform　distribution　of　microdefects　can　be　considered　a　special　example　of　the　present　study.　In　addition,　the　particle　velocity　transmission　coefficient　and　energy　transmission　coefficient　are　always　less　than　1.0.　However,　when　the　gradient　is　large　and　the　frequency　is　small,　the　particle　stress　transmission　coefficient　is　larger　than　1.0,　which　shows　that　the　particle　stress　amplitude　in　a　rock　mass　with　a　microdefect　gradient　distribution　will　be　amplified.