The invention discloses a method for molding powder calcium oxide. The method comprises the following steps: pressing powder calcium oxide to a certain shape by using a tablet press or other pressing machines, introducing a gas with carbon dioxide or water vapor, after a certain time, introducing a flue gas of a certain temperature, thereby preparing calcium oxide of certain granularity and strength from the powder calcium oxide. By adopting the method, calcium carbide can be produced from quick lime which is prepared from decomposed powder calcium oxide instead of limestone, the powder calcium oxide is a byproduct of production of sulfuric acid produced from gypsum which is an industrial byproduct, and thus the raw material source of the calcium carbide industry can be widened.