Abstract: During 2016 and 2021, sample plots were established and investigated on diversity and seasonal change of Diptera in 4 different habitats of Hangzhou Bay Wetland, Zhejiang province. The results showed that there were 98 species of 18 families Diptera, among which Chironomidae, Agromyzidae, Ephydridae, Anthomyiidae, Syrphidae and Drosophilidae were abundant. The insect number, diversity and richness index of Diptera in constructed wetlands and artificial experimental forests were significantly higher than those in natural tidal flat wetland and coastal tidal flat wetlands. The insect number, richness and diversity index of Diptera were the highest in spring and summer, while the richness and diversity index were lower in autumn and winter.