The　problem　of　target　detection　and　localization　in　layered　media　can　be　solved　by　the　mixed　TR-RTM.　The　highlight　of　this　paper　is　on　multilayer　media,　where　the　target　is　harder　to　detect　than　in　double-layered　media,　due　to　the　interference　of　multiple　interface　reflection　signals.　The　core　idea　of　the　TR-RTM　mixed　method,　namely　the　RTM　isochronism　principle,　is　applied　for　the　three　cases.　Typically,　a　target　under　a　TR-RTM　process　can　form　a　mountain-like　acoustic　field　distribution.　For　the　interface　whose　reflected　signal　is　an　interference,　the　acoustic　field　distribution　is　disordered　and　inhomogeneous,　with　a　smaller　amplitude.　The　TR-RTM　greatly　improves　the　signal-to-interference　ratio,　where　the　position　of　the　summit　is　the　just　position　of　the　target,　thus,　detecting　and　localizing　the　target.