Two　new　Brönsted　acidic　ionic　liquids　were　prepared　and　characterized　by　NMR　and　FTIR.　Their　catalytic　activities　for　the　synthesis　of　biodiesel　fuel　via　transesterification　of　tung　oil　with　methanol　were　evaluated　and　compared　to　that　of　two　imidazole-based　ionic　liquids　for　the　first　time.　Among　them,　[Ps-N-Ch(Me)2][p-TSA]　exhibited　the　highest　catalytic　activity　and　was　chosen　as　catalyst　for　further　research.　A　study　on　optimizing　the　reaction　conditions　was　performed　by　orthogonal　experiment　based　on　the　single　factor　experiment.　It　was　found　that　the　ranking　of　the　significance　of　factors　on　the　biodiesel　yield　is　as　follows:　molar　ratio　of　methanol　to　oil　＞　reaction　temperature　＞　reaction　time　＞　catalyst　dosage.　The　maximum　biodiesel　yield　reaches　98.98%　under　the　optimal　reaction　conditions　at　a　molar　ratio　of　methanol　to　oil　of　21:1,　a　reaction　temperature　of　120　°C,　a　reaction　time　of　2　h　and　a　catalyst　dosage　of　5.0　wt.%.　Moreover,　the　reusability　experiment　exhibits　that　the　catalyst　can　be　reused　five　times　with　negligible　loss　of　the　activity.　The　refined　biodiesel　meets　the　biodiesel　standard　ASTM　D6751-07,　which　can　be　used　as　fuel　in　diesel　engines.　©　2016　Institution　of　Chemical　Engineers