In order to reduce the amount of ionic liquids, used silica to designed and synthesized supported ionic liquids which was synthesized from morpholin. The silica-ILs catalyst was characterized by FT-IR spectroscopy, thermogravimetric analysis and N2 adsorption-desorption. And the catalytic performance of the catalyst was measured for esterification reaction. The results showed: n(cis-butenedioic anhydride):n(ethanol)=1:3.5, the mass of catalyst [Silica-Ps-Mor]HSO4 is 5% of the quality of cis-butenedioic anhydride, water carrying agentreaction is 30 mL, temperature is 90 ℃, reaction time is 4 h, the yield of diethyl maleate was up to 94.5%. The supported catalyst could be easily separated from the reaction system and reused at least eight times without loss of catalytic activity.