Soft　manipulators　have　garnered　significant　research　attention　in　recent　years　due　to　their　flexibility　and　adaptability.　However,　the　inherent　flexibility　of　these　manipulators　imposes　limitations　on　their　load-bearing　capacity　and　stability.　To　address　this,　this　study　compares　various　variable　stiffness　technologies　and　proposes　a　novel　design　concept:　leveraging　the　phase-change　characteristics　of　low-melting-point　alloys　(LMPAs)　with　distinct　melting　points　to　fulfill　the　variable　stiffness　requirements　of　soft　manipulators.　The　pneumatic　structure　of　the　manipulator　is　fabricated　via　3D-printed　molds　and　silicone　casting.　The　manipulator　integrates　a　pneumatic　working　chamber,　variable　stiffness　chambers,　heating　devices,　sensors,　and　a　central　channel,　achieving　multi-stage　variable　stiffness　through　controlled　heating　of　the　LMPAs.　A　steady-state　temperature　field　distribution　model　is　established　based　on　the　integral　form　of　Fourier’s　law,　complemented　by　finite　element　analysis　(FEA).　Subsequently,　the　operational　temperatures　at　which　the　variable　stiffness　mechanism　activates,　and　the　bending　performance　are　experimentally　validated.　Finally,　stiffness　characterization　and　kinematic　performance　experiments　are　conducted　to　evaluate　the　manipulator’s　variable　stiffness　capabilities　and　flexibility.　This　design　enables　the　manipulator　to　switch　among　low,　medium,　and　high　stiffness　levels,　balancing　flexibility　and　stability,　and　provides　a　new　paradigm　for　the　design　of　soft　manipulators.　©　2025　by　the　authors.