Natural rivers are divided into the riverine and lacustrine zones owing to the construction of cascade reservoirs. However, changes in habitat conditions have significant effects on the spatial distribution of fish and changes in ecological types. Changes in fish species composition, dominant species, community diversity and variation in fish ecological types between riverine and lacustrine zones were used to evaluate the effects of fish habitat. Data were obtained from the fishery survey in May 2018 and previous literature. The results showed that the number of fish species decreased and the rate of decrease slowed, whereas the proportion of big fish species increased after the construction of cascade reservoirs. The dominant species were constantly changing under the influence of habitat changes, and the ecological types of fish in the riverine and lacustrine zones were different. The species that inhabit the slow-flow zone, the middle and lower layers of water flow, and require initial spawning water temperature higher than 18℃ were the dominant ecological types. Finally, the study showed that because of fish autecology, there were distinct patterns in fish spatial distribution and community structure characteristics affected by the operation of high dam reservoirs. The riverine and lacustrine zones caused by the hydrodynamic variation of cascade reservoir construction were the internal driving force for the changes in fish community ecological types.