The combination of lanthanum(iii) triflate, sulfur, and dimethyl sulfoxide prompted a facile, direct preparation of 2,5-diformylfuran from glucose and fructose. The one-step dehydration/oxidation of fructose afforded 2,5-diformylfuran in an excellent yield with high selectivity. The proposed mechanism, large-scale synthesis, and product separation were presented. This approach represents a straightforward and eco-friendly pathway, which can be applied in the large-scale production of 2,5-diformylfuran from fructose.