In this study， water-insoluble dietary fiber （IDF） was extracted from kelp and wheat bran by enzyme-assisted chemical methods， and the in vitro functional properties of the IDF samples were evaluated. The results showed that the extraction yields for kelp and wheat bran IDF were 8.52% and 77.93%， respectively. The swelling capacity of kelp IDF was 5.99 mL/g， the water holding capacity was 11.82 g/g， and the oil holding capacity was 10.05 g/g. The swelling capacity of wheat bran IDF was 3.10 mL/g， the water holding capacity was 5.97 g/g， the oil holding capacity was 5.95 g/g. In terms of the binding capacity for lead and cadmium ions， the kelp IDF reached 683.61 μg/g and 528.97 μg/g， respectively； the bran IDF was 583.23 μg/g and 548.09 μg/g， respectively. Kelp derived IDF had excellent functional characteristics， showing great application potential for the development of marine functional food.