In　this　paper,　the　blasting　vibration　of　rock　is　analyzed　under　the　condition　of　multi-free　surfaces,　which　is　based　on　the　excavation　of　a　collapse　cavity　section　in　the　extension　of　the　existing　tunnel.　The　effect　of　simulating　blasting　vibration　on　the　reinforcement　area　of　the　collapse　cavity　and　surrounding　rock　is　investigated　by　a　fully　restarted　numerical　method　and　Lagrangian　algorithm　method.　Furthermore,　vibration　velocities　and　the　attenuation　law　of　characteristic　points　are　obtained.　It　is　found　that　the　maximum　vibration　velocities　calculated　by　the　numerical　method　are　in　accordance　with　the　requirement　of　the　safety　of　blasting　vibration.　It　also　verifies　the　feasibility　of　blasting　design,　and　can　be　used　a　guide　for　the　blasting　construction.　Meanwhile,　the　blasting　vibration　monitoring　of　collapse　section　excavation　is　also　conducted.　The　obtained　vibration　velocities　from　field　experiments　with　the　numerical　simulation　are　in　a　good　agreement.　The　results　indicate　that　numerical　methods　can　be　used　to　describe　the　rock　fragmentation　and　blasting　vibration　well　in　the　millisecond　delay　blasting.　Therefore,　the　current　study　shows　a　good　example　for　the　similar　engineering　conditions.　©　2016,　Science　Press.　All　right　reserved.