Abstract: The adjacent water systems of the Dalinor Wetlands include the Chagannor water system, the Wulagai Basin water system and the Xiliao River-Xilamulun River system. Based on the data of field surveys since 2019, the status of fish diversity in the Dalinor Wetlands and its adjacent water systems was studied, and the formation, distribution pattern and changes of fish diversity have been discussed. We also analyzed the fish diversity relationship between the Dalinor wetlands and the fish diversity of its adjacent water systems, and propose ways for sustainability and development of fish diversity. The results showed that the fish assemblage of the Dalinor wetlands consisted of 3 orders, 5 families, 20 genera, 24 species, belonging to 6 ecological groups. The fish assemblage of the Chagannuor water system consisted of 2 orders, 3 families, 14 genera, 15 species, belonging to 5 ecological groups. The fish assemblage of the Wulagai Basin was composed of 2 orders, 3 families, 12 genera and 13 species, belonging to 4 ecological groups. The fish assemblage of the Xiliao River-Xilamulun River system was composed of 6 orders, 12 families, 40 genera, 46 species, belonging to 6 ecological groups. In total, the fish assemblage of the Dalinor Wetlands and its adjacent water systems was composed of 6 orders, 12 families, 40 genera, 48 species, belonging to 6 ecological groups. Fisheries activities have increased the fish diversity and the fish community correlations between the Dalinor Wetlands and its adjacent water system and they shared the same ecological groups of fish, but there was no close relationship between them. The rational use of fishery resources should be combined with the ecological construction of the wetland to protect the fish diversity of the Dalinor wetlands and its adjacent water systems, to realize the sustainable development of fish diversity and fishery at the same time.