It was reported that biodiesel was made through transesterification of olive oil by methanol using KOH as catalyst.The reaction conditions were reviewed such as the amount of methanol and catalyst,reaction time and temperature.Through orthogonal analysis of parameters in a four-factor and three-level test,the optimum conditions were obtained:reaction temperature 70℃,reaction time 100 min,15％ methanol and 1.0％ KOH based on oil weight.Under these conditions the conversion rate was up to 95.2％.