The present disclosure provides a method for preparing a 7α-alkoxyoxacephem intermediate compound, the method comprising a process (S1) including: reacting a compound represented by a following chemical formula 1 with a halogen compound in an organic solvent to form a reaction product such that unreacted halogen compound remains; and adding metal alkoxide and reducing agent to the reaction product with the unreacted halogen compound remaining, thereby to produce a compound represented by a following chemical formula 2: where R is a Cl, Br, I, halogen derivative, R1 is a carboxyl protecting group including diphenylmethyl, p-methoxybenzyl, p-nitrobenzyl or hydrogen (H), and R2 is an alkyl group having 1 to 4 carbon atoms.