Unusual　self-solidifying　tris(2,4,6-trimethoxyphenyl)-phosphonium-containing　ionic　liquids　were　synthesized　for　biodiesel　production　via　the　catalytic　esterification　of　a　variety　of　free　fatty　acids.　These　ionic　liquids　were　synthesized　by　a　two-step　method　involving　the　reaction　between　tris(2,4,6-trimethoxyphenyl)-phosphine　and　1,3-propanesulfonate　to　form　a　TTMPP-PS　zwitterion　followed　by　acidification　with　different　acids.　The　obtained　solid-state　ionic　liquids　were　soluble　during　the　reaction　to　conduct　homogeneous　catalysis　and　precipitated　after　the　reaction,　which　was　followed　by　alcohol　evaporation,　indicating　the　great　ease　of　heterogeneous　recovery;　therefore,　the　ionic　liquids　had　the　combined　advantages　of　both　homogeneous　and　heterogeneous　catalysts.　As　a　result,　such　ionic　liquids　show　great　potential　for　biodiesel　production　because　of　their　pronounced　activity,　excellent　stability,　and　recyclability.