The Cu/Al₂O₃ ester hydrogenation catalyst was prepared by ultrasonic enhanced coprecipitation method，and the catalyst was modified by adding alkaline earth metal nitrate.The effect of alkaline earth metals and added percent content on the hydrogenation performance of the catalyst was investigated by hydrogenation of dimethyl bisate.The catalyst was characterized by X-ray diffraction（XRD），temperature-programmed reduction（H₂-TPR），temperature-programmed desorption of ammonia（NH₃-TPD），surface area and pore structure analysis to research the effects of alkaline earth metal calcium addition on the crystal structure，reduction performance，acid strength，BET specific surface area and pore structure of the catalyst were investigated.The results showed that the alkaline earth metal modification could improve the hydrogenation performance of the catalyst.Under the conditions of temperature of 160 ℃，pressure of 6.0 MPa，space velocity of 0.6 h^-1 and the molar ratio of the hydrogen ester material was 300，the conversion rate of dimethyl succinate could reach 99.46%，and the selectivity of 1，4-butanediol could reach 94.39%.After adding an appropriate amount of calcium，the characteristic peaks of the active components in the catalyst became wider and the dispersion was increased.The reduction temperature was slightly decreased.The acid strength was significantly decreased.The surface area was slightly decreased，pore volume was slightly increased，pore size was significantly increased.These changes of physicochemical properties led to the change of hydrogenation performance of dimethyl succinate catalyst.