In this study to prepare longan seed activated carbon with sulfonic acid group for esterification of palm fatty acid distillate (PFAD) to produce methyl ester for biodiesel. The longan seed was activated with NaOH in various condition (LSAC) following sulfonation with concentrated H2SO4 under reflux condition to obtain sulfonic acid group onto structure of longan seed activated carbon (LSAC-SO3H). The LSAC-SO3H exhibited the amorphous carbon structure, specific surface area 1100-2160 m?/g, average pore volume 0.5158-1.1030 cm3/g, average pore diameter 9.27-10.23 ? and acid amount 0.31-0.46 mmol/g. The esterification of palm fatty acid distillate with methanol were studied at 80oC, PFAD:MeOH radio as 1:4, catalyst amount as 3 wt. % and 8 hours. The esterification study found that LSAC-A-SO3H exhibited the highest conversion of free fatty acid than LSAC-B-SO3H. In addition, LSAC-A-SO3H had reusability in esterification for 4 times.