The present disclosure relates to a method for preparing a disubstituted urea and carbamate compounds simultaneously through a one-pot reaction of an amine, carbon dioxide and an alkylene oxide compound in the presence of an ionic liquid-based complex catalyst system containing indium. In accordance with the present disclosure, a disubstituted urea and carbamate compounds can be prepared simultaneously at high yield. In addition, the ionic liquid-based catalyst containing indium according to the present disclosure is economical because it can be reused several times.