Abstract: In this paper, the flume test was conducted to study the effects of different substrate, flow conditions and geomorphology on the habitat of crabs. The results showed that crabs had the strongest preference to the pebble bed, followed by coarse sand and gravel. The flow velocity was 0.8 m/s when the crabs reached greatest adhesive force on the pebble bed. The crabs number on the longitudinal strip of pebble bed was the highest, followed by local pit landform, and transverse strip was the worst landform. Therefore, the combination of pebble sediment, low flow velocity and longitudinal strip geomorphologic characteristics can protect the crabs habitat to the greatest extent.