Abstract: The synthetic catalyst of methyl isopropyl ketone is often prepared by the active metal salts，using alumina as the supporter in China now.The key of synthesizing methyl isopropyl ketone is the preparation technology of catalyst.In order to improve the selectivity of catalyst and the yield of product，methyl isopropyl ketone was synthesized with isobutyric acid and acetic acid as the raw materials，and Ln/TiO↓2 as the catalyst.Influences of active components of the catalyst，temperature of catalytic synthesis reaction，mixture ratio of isobutyric acid and acetic acid and catalyst regeneration etc.on the catalytic synthesis reaction were investigated.The optimum reaction conditions were obtained as follows：mass fraction of active component of rare earth is 15%；reaction temperature is 430~450 ℃；amount-of-substance ratio of isobutyric acid to acetic acid is 1.0∶1.5；and reaction space velocity is 0.6~0.7 h↑-1.Percent conversion of over 90% and selectivity of over 80% were attained under the optimal conditions.