To　further　investigate　the　compressive　mechanical　properties　of　new　mold　bag　concrete　for　primary　support　of　tunnels,　the　original　test　procedure　is　improved　to　fulfill　the　actual　construction　requirements　of　mold　bag　concrete　during　specimen　processing.　Accordingly,　various　test　conditions　are　created　for　specimens　aged　3,　7,　and　28　days,　and　the　influence　of　these　mold　bags,　pressurized　drainage　pressures,　and　pressurized　drainage　times　on　the　compressive　mechanical　properties　of　the　concrete　are　analyzed,　along　with　the　failure　modes　of　the　specimens　under　various　working　conditions.　The　present　findings　are　stated　as　follows:　(1)　The　mold　bags　significantly　improve　the　compressive　strength　and　overall　deformation　capacity　of　the　concrete.　(2)　The　overall　deformation　capacity　and　compressive　strength　of　the　mold　bag　concrete　vary　with　the　pressurized　drainage　pressure　and　pressurized　drainage　time,　and　the　pressurized　drainage　pressure　over　a　certain　time　provides　a　greater　enhancement　than　the　pressurized　drainage　time　under　a　certain　pressure.　(3)　The　normal　concrete　specimens　are　damaged　in　the　shape　of　an　angular　cone,　the　nonmold　bag　concrete　specimens　are　damaged　along　the　parallel　direction　of　the　applied　load,　and　the　mold　bag　concrete　specimens　display　a　petal　shape　from　the　front　view.　©　2022,　Editorial　Office　of　Tunnel　Construction.　All　rights　reserved.