The oxidation characteristics and energy releasing characteristics of MgB₂ were studied using oxygen bomb calorimeter, thermal analyzer and tube furnace. Results show that the combustion heat and combustion efficiencies of MgB₂ are all higher than those of amorphous boron. In the temperature range explored (298-1673 K), four successive phases are observed in the oxidation process of MgB₂ under slow heating rate. The primary oxidation stage of MgB₂ occurrs between 1200 K and 1665 K. However, the primary oxidation stage of amorphous boron occurrs nearly 1919 K. At 1665 K, the oxidation percentage of MgB₂ is 94.3%, compared to 43.6% of amorphous boron. Compared with amorphous boron, the fact that complete oxidation of MgB₂ can be achieved at lower temperature indicates its superiority.