Lamb　wave　technology　is　a　promising　technology　in　the　field　of　structural　health　monitoring　and　can　be　applied　in　the　detection　and　monitoring　of　defects　in　plate　structures.　Based　on　the　reconstruction　algorithm　for　the　probabilistic　inspection　of　damage　(RAPID),　a　Lamb-based　detection　and　evaluation　method　of　through-thickness　rectangular　notches　in　metal　plates　was　proposed　in　this　study.　The　influences　of　through-thickness　rectangular　notch　length　and　the　angle　between　sensing　path　and　notch　length　direction　on　signals　were　further　explored　through　simulations　and　experiments.　Then　a　damage　index　calculation　method　which　focuses　on　both　phase　and　amplitude　difference　between　detected　signals　and　baseline　signals　was　proposed.　Based　on　the　damage　index　difference　between　two　vertically　crossed　sensing　paths　which　pass　through　the　notch　in　a　sensor　network,　the　notch　direction　identification　method　was　proposed.　In　addition,　the　notch　length　was　determined　based　on　the　damage　index　distribution　along　sensing　paths.　The　experimental　results　showed　that　the　image　reconstructed　with　the　proposed　method　could　reflect　the　information　for　the　evaluation　of　notches.