The MgO samples are prepared by heating Mg(OH) 2 at 600 ℃ in different atmospheres. The XRD results show that Mg(OH) 2 is decomposed into MgO after calcination. The results of BET indicate that the specific surface area of the samples is affected by the calcination atmosphere, the sample preheated in vacuum has the highest surface area, while the sample preheated in air has the lowest surface area. The CO 2 TPD profiles of the samples are also different, which implies that the samples have different surface basicity. From the desorbed amount of CO 2 and the desorption activation energy, it is found that the sample pretreated in vacuum has the most basic sites and the strongest basicity. The MgO samples were prepared by heating Mg (OH) 2 at 600 ° C in different atmospheres. The XRD results show that Mg (OH) 2 is decomposed into MgO after calcination. The results of BET indicates that the specific surface area of ​​the samples is affected by the calcination atmosphere, the sample preheated in vacuum has the highest surface area, while the sample preheated in air has the lowest surface area. The CO 2 TPD profiles of the samples are also different, which implies that the samples have different surface basicity From the desorbed amount of CO 2 and the desorption activation energy, it is found that the sample pretreated in vacuum has the most basic sites and the strongest basicity.