Photodynamic　therapy　(PDT)　is　a　promising　and　non-invasive　treatment　for　various　cancers.　Although　nuclear　PDT　has　considerable　therapeutic　prospects,　it　is　still　hindered　by　the　non-specific　recognition　of　tumor　tissues　or　the　degradation　of　nuclear　targeting　cationic　groups　by　enzymes　in　the　blood.　Herein,　a　hierarchical　targeted　and　controlled　release　strategy　is　proposed　by　using　folate-modified　poly-β-cyclodextrin　(poly-β-CD)　as　a　nano-carrier　for　loading　nuclear　localization　signals　(NLSs)-conjugated　photosensitizer　PAP　(PAP　=　pyropheophorbide　a—PAAKRVKLD).　Excitingly,　the　obtained　FA-CD@PAP　(FA　=　folic　acid)　and　nanoparticles　(NPs)　can　specifically　recognize　tumor　cells　overexpressing　folate　receptors　(FR)　to　remarkedly　enhance　the　intracellular　accumulation.　Furthermore,　the　encapsulated　PAP　can　be　released　under　acidic　conditions　to　realize　precise　nuclear　localization.　The　reactive　oxygen　species　(ROS)　generated　by　the　intranuclear-accumulated　PAP　upon　irradiation　can　oxidize　and　destroy　DNA　chains　or　DNA　repair　enzymes　instantaneously,　which　can　directly　induce　cell　death.　As　a　result,　FA-CD@PAP　NPs　exhibit　excellent　tumor　regression　and　negligible　side　effects.　This　work　provides　an　intelligent　nuclear-targeted　delivery　strategy　for　in　situ　nuclear　PDT　with　extremely　prominent　efficacy　and　high　biological　safety.[Figure　not　available:　see　fulltext.]　©　2021,　Tsinghua　University　Press　and　Springer-Verlag　GmbH　Germany,　part　of　Springer　Nature.