Abstract: A sulfonated cardon solid-acid catalyst was prepared, and its characterization was studied by FT-IR spectra, elemental analysis(EA), X-ray diffraction(XRD) and thermogravimetrical analysis(TGA). The catalyst was used in transesterification of Jatropha curcas L. seed oil with methanol, and effects of various factors on transesterification were studied. The contents of TG, DG, MG and FAME were analyzed by HPLC analysis. The result showed that it was very effective for the transesterification of J. curcas seed oil with methanol catalyzed by sulfonated cardon solid-acid catalyst, and the optimum reaction condition (the ratio of methanol to oil 12:1 ) was:ratio of catalyst to J.curcas oil (mass fraction) 10%, reaction temperature 120℃, reaction time 8h, fatty acid content less than 10% in J.curcas oil, water content less than 5% in J.curcas oil. The conversion rate of transesterification was up to 95%, which was not decreasd when the catalyst was used for 10 times.