The present invention relates to a method for olefin oligomerization, and can provide a method for olefin oligomerization. The method includes the steps of: introducing an oligomerization transition metal catalyst, olefin monomers, and a solvent into a reactor and performing an olefin oligomerization reaction to produce an oligomer; introducing a catalyst deactivator to a reaction product of the oligomerization reaction to deactivate the catalyst, with the catalyst deactivator including at least one functional group containing at least one selected from the group including oxygen, phosphor, nitrogen, and sulfur and having a number average molecular weight of 400 or more; separating the oligomer through distillation in a distiller; and separating the catalyst deactivator through the bottom end of the distiller.