Traditional　quadruped　robots　are　known　for　their　agile　movement　and　versatility　across　varied　terrains.　However,　their　foot　structures　struggle　to　navigate　unstructured　terrains　such　as　pipes,　slopes,　and　protrusions.　This　paper　proposes　a　novel　tensegrity　foot　structure　consisting　of　a　tensegrity　ankle　joint　and　an　X-shaped　adaptive　tensegrity　footpad,　which　enhances　the　terrain　adaptability　of　legged　robots.　The　equilibrium　equation　of　the　ankle　joint　is　established,　and　the　relationship　between　the　translational　stiffness　of　the　ankle　joint　and　the　spring　stiffness　is　derived.　Additionally,　a　mathematical　model　for　the　number　of　X-shaped　tensegrity　footpad　units　and　their　relationship　with　the　deformation　height　and　length　of　the　tensegrity　footpad　is　established.　A　physical　prototype　of　the　tensegrity　foot　was　fabricated　using　3D　printing.　Experiments　are　conducted　to　validate　the　adaptability　of　both　the　ankle　joint　and　the　tensegrity　footpad.　The　results　indicate　that　the　proposed　adaptive　tensegrity　foot　structure　exhibits　good　adaptability　on　unstructured　terrains　with　varying　radii,　slopes,　steps,　S-curves,　and　spherical　surfaces.　The　tensegrity　foot　structure　can　enhance　the　environmental　adaptability　of　quadruped　robots　and　has　excellent　impact　resistance　effects.