Inspired　by　intelligent　biomaterials　which　often　have　flexible　responsiveness　to　multiple　environmental　cues　and　strengthen　their　mechanical　properties　by　trainings,　emerging　soft　actuators　require　programmable　manipulation.　Currently,　the　integration　of　such　characteristics　as　rapid　self-strengthening,　strain-adaptive　stiffening　and　smart　actuation,　into　a　single　hydrogel　actuator　is　urgently　needed.　Here,　we　report　a　self-strengthened　hydrogel　actuator　based　on　the　semi-interpenetrating　polymer　network　consisting　of　polyvinyl　alcohol　(PVA)　and　poly(N-isopropylacrylamide)　(PNIPAm),　which　can　display　diverse　programmable　actuations　by　responding　to　temperature/salt　stimuli.　In　the　design,　the　layer　of　freeze-thawed　PNIPAm/PVA　(PPGel-F)　is　assembled　with　another　original　PNIPAm/PVA　hydrogel　layer　(PPGel)　into　one　device.　By　taking　advantage　of　the　PVA　crystalline　nanofibrils　in　the　PPGel-F　matrix,　the　differentiated　swelling　degree　across　the　bilayer　structure　gives　rise　to　asymmetric　deformations　and　the　resultant　shape　transformation.　Moreover,　upon　the　mechanical　training　with　less　than　100　cycles,　the　anisotropic　arrangement　of　PVA　nanofibrils　through　strong　hydrogen　bonding　interactions　can　swiftly　immobilize　the　amorphous　polymer　chains　orientation　along　the　tensile　direction.　This　enhances　the　strain-induced　crystallization,　thereby　generating　the　rapid　self-　strengthening　behavior.　The　proposed　work　provides　potential　solution　for　constructing　dynamically　adaptive　hydrogel　systems　that　can　mimic　biological　tissues　for　more　intelligent　soft　robotics　and　bionic　research.　©　2023　Elsevier　Ltd