Knoevenagel condensation reaction is one of the most important industrial reactions, the products obtained from which are widely used in the synthesis of important chemicals, drugs and biological compounds. The purpose of this article is to present a new and efficient catalytic system for performing the condensation reaction of Knoevenagel. In this research, solid alkaline catalysts containing a mixture of barium-magnesium oxides with different molar ratios were prepared and then calcined. The prepared catalysts were characterized by different techniques. The results showed that the mixture of MgO/ BaO oxides were well formed. The condensation reaction of benzaldehyde and ethyl acetoacetate was studied in the presence of synthesized catalysts and methanol solvent. The effect of various parameters in catalyst synthesis such as Ba/Mg molar ratio and calcination temperature were investigated. The results showed that the BaO/MgO catalyst sample with a molar ratio of 4:6 and a calcination temperature of 1050 °C shows more catalytic activity. In addition, the effect of various factors on the reaction, such as the effect of temperature, amount of catalyst, reaction time, effect of solvent, effect of the ratio of ethyl acetoacetate to benzaldehyde and the reusability of the catalyst were studied. According to the obtained results, in the presence of 0.1 g of catalyst, with the molar ratio of ethyl acetoacetate to benzaldehyde 1:1, reaction time 10 h, temperature 80˚C and in methanol solvent, the conversion percentage of benzaldehyde and the selectivity percentage of the main product are 94% and 80% respectively.