Two-step catalyzed process was used to prepare biodiesel from jatropha oil. The first step was that the free fatty acid from jatropha oil and methanol was pre-esterified by the solid acid catalyst SiO2/Zr(SO4)2-Ti(SO4)2；The second step was that alcoholysis reaction within jatropha oil and methanol was catalyzed by base catalyst K2CO3/MgO-Al2O3 . The reaction conditions were optimized by single factor test and orthogonal test. The results showed that the optimal esterification conditions were with catalyst amount of 2%, the molar ratio of methanol to oil 12∶1, reaction temperature 75 ℃, reaction time 2 h, and the acid value reduced from 10.47 mg KOH/g to 0.70 mg KOH/g. The optimal alcoholysis reaction conditions were catalyst amount of 2%, molar ratio of methanol to oil 12∶1, reaction temperature 65 ℃, reaction time 2 h, and the alcoholysis conversion rate was around 95%. Two〖CD*2〗step catalytic method was suitable for preparing biodiesel from jatropha oil, and the results laid some theoretical foundation for the industrial production of biodiesel.