Abstract: ST(SO42-/TiO2) solid acid was prepared by direct calcination of industrial metatitanic acid.The ST solid acid showed a high catalyst activity for the esterification of methanol and free fatty acid in Jatropha curcas L.seed oil with high acid value.The effects of various conditions of preparation of ST solid acid on its activity were investigated.Calcination temperature is a vital factor and calcination duration is a subsidiary factor in preparation of ST solid acid.The optimum condtition was 2 hrs at 500 ℃.The optimum conditions for the esterification were 2 hrs at 90 ℃,4% solid acid and 20:1 methanol to FFA.Under these conditions,the conversion of FFA was higher than 97%.It was indicated by FTIR and S determination of ST solid acid that the deactivity of the catalyst was mainly caused by the loss of active species in polar solvent and surface coking.Resulfuration and calcinations in oxygen may be an effective way to regenerate the activity of ST solid acid.