Ecological surveys in Tian-e-zhou Oxbow and Laojianghe Oxbow along the middle reaches of Yangtze River were carried out during April 2003 to February 2004. Results indicated that macrozoobenthos communities of oxbows were similar to those of river-isolated lakes in the composition of standing crops, dominated by gastropods and aquatic insects, but were richer in potamophilus and psychrophilic species. Compared with the data of 1990’s, biomass of macrozoobenthos decreased by 48.3%-78.6%, mainly due to the decline of mollusks. The resource deterioration was mainly ascribed to overfishing and river-lake disconnection. Comparison with other types of Yangtze waters indicated that the floodplain waterbodies with an intermediate level of hydrological connectivity have the highest species biodiversities of macrozoobenthos, and have abundant mollusks， especially bivalves. To restore the important function of the oxbows in maintaining biodiversity of the Yangtze floodplain, it is suggested to stock animals rationally and to reconnect with the Yangtze River as frequently as possible.