Silicone　foam　materials　with　unique　inorganic/organic　molecular　networks　and　porous　structures　are　widely　used　in　many　emerging　fields　from　aerospace　to　new　energy　fields.　However,　current　silicone　foam　materials　still　show　some　limitations,　such　as　the　relatively　high-density　values　of　＞200　mg　cm(-3)　,　complex　fabricating　process　and　difficulty　in　tailoring　pore　structure.　Herein,　we　report　a　large-scale　and　facile　fabricating　strategy　to　prepare　phenyl-containing　silicone　foam　materials　(PhSiRF)　with　ultra-lightweight　feature,　tunable　pore　structure,　and　excellent　wide-temperature　mechanical　flexibility.　Interestingly,　the　presence　of　phenyl　groups　onto　the　Si　-　O　-　Si　backbone　tailors　the　chemical　foaming　rate　probably　due　to　the　steric　hindrance　effect,　thus　producing　tunable　pore　size　distributions　in　the　range　of　180　-　500　mu　m.　Typically,　the　PhSiRF　with　50　%　phenyl　groups　not　only　shows　a　very　low　density　of　similar　to　100　mg　cm(-3)　,　superior　to　previous　silicone　foams　and　composites,　but　also　exhibits　wide-temperature　flexibility　(stable　compressive　strain　of　80　%　from　-90　to　210degree　celsius)　and　excellent　thermal　insulation　performance,　which　outperforms　those　of　conventional　polymer　foams　including　polyurethane,　polyethylene　and　melamine　foams.　Based　on　the　structure　observation　and　theory　analysis,　the　influence　of　different　pore　morphological　structures　on　the　thermal　insulation　performance　is　discussed　and　demonstrated.　Clearly,　this　work　provides　a　new　yet　simple　method　for　developing　high-performance　silicone　rubber　foam　materials　for　promising　thermal　insulation　applications.