Sparse　decomposition　is　a　promising　approach　for　Lamb　wave　structural　health　monitoring.　In　Lamb　wave　sparse　decomposition,　designing　an　appropriate　dictionary　is　of　vital　importance,　which　should　be　as　accurate　to　actual　wave　packet　as　possible.　Dispersion　and　multi-mode　characteristics　have　been　used　for　dictionary　design.　However,　none　of　the　previous　research　considered　amplitude　modulation　in　dictionary　design,　which　limits　the　performance　of　sparse　decomposition.　To　solve　this　issue,　modified　dictionary　design　for　Lamb　wave　sparse　decomposition　is　proposed　in　this　study.　First,　frequency-dependent　amplitude　modulation　curve　is　obtained　based　on　the　prior　information　of　plate　thickness,　the　type　of　mode,　and　the　transducer　size.　Second,　amplitude　modulation　is　placed　on　the　Lamb　wave　propagation　model　to　redesign　the　dictionary.　An　experiment　is　given　to　validate　the　effectiveness　of　Lamb　wave　sparse　decomposition　with　the　modified　dictionary　design.　©　APWSHM　2018.　All　rights　reserved.