Novel MgO-SBA-15 supported catalysts were prepared for oxidative esterification of methacrolein (MAL) with methanol to methyl methacrylate (MMA). The MgO-SBA-15 supports were synthesized with different magnesia loadings from different magnesium precursors and hydrochloric acid molar concentrations. The MgO-SBA-15 supports and Pd-Pb/MgO-SBA-15 catalysts were characterized by several analysis methods. The results revealed that the addition of MgO improved the ordered structure of SBA-15 supports and provided surface alkalinity of SBA-15 supports. The average size of the Pd3Pb particles on magnesia-modified Pd-Pb/MgO-SBA-15 catalysts was smaller than that on the pure silica-based Pd-Pb/SBA-15 catalysts. The experiments on catalyst performance showed that the magnesia-modified Pd-Pb/MgO-SBA-15 catalysts had higher activity than pure silica-based Pd-Pb/SBA-15 catalysts, showing the strong dependence of catalytic activity on the average size of active particles. The difference of activity between Pd-Pb/SBA-15 catalysts and Pd-Pb/MgO-SBA-15 catalysts was due to the discrepant structural properties and surface alkalinity provided by MgO, which led to the different Pd3Pb particle sizes and then resulted in the different number of active sites. Besides magnesia loadings, other factors, such as hydrochloric acid molar concentration and magnesium precursors, had considerable influences on the catalytic activity. (C) 2014 The Chemical Industry and Engineering Society of China, and Chemical Industry Press. All rights reserved.