A　split　three-characteristics　method　was　proposed　that　can　be　used　to　analyze　the　stress　wave　propagation　through　a　rock　mass　with　double-scale　discontinuities　(micro-defect　(MD)　and　macro-joint　(MJ)).　The　mechanisms　of　the　effects　of　MDs　and　MJs　on　stress　wave　propagation　were　investigated.　The　characteristic　lines　were　divided　into　the　three　basic　elements　of　triangle,　diamond　and　separated　diamond　elements　to　calculate　the　stress,　strain　and　velocity　of　the　stress　wave　propagation　through　a　rock　mass　with　double-scale　discontinuities　(MD-MJ).　The　results　show　that　the　effects　of　MJ　on　stress　wave　propagation　are　related　to　the　macro-joint　stiffness,　while　the　effects　of　MDs　on　stress　wave　propagation　are　related　to　the　viscous　coefficient　and　propagation　distance.　The　comparison　of　the　stress　wave　propagation　through　MJs　and　MD-MJs　shows　that　the　traditional　MJ　model　can　be　regarded　as　a　special　case　of　the　present　MD-MJ　model　and　the　effects　of　MDs　can　be　neglected　when　the　propagation　distance　is　sufficiently　short.　However,　when　the　propagation　distance　is　long,　the　effects　of　MDs　must　be　considered.　The　results　also　show　that　the　present　characteristics　method　can　be　used　to　investigate　the　stress　wave　propagation　through　double-scale　discontinuities　efficiently.