Eighty five species of aquatic and semi-aquatic Heteroptera belonging to 14 families are reported from Xishuangbanna and nearby counties in Yunnan. Collecting locations and habitats are given. Ten species (Hydrometra jaczewskii, H. longicapitis, H. orientalis, Amemboa (Amemboa) sexualis, A. (A.) lyra, Metrocoris ciliatus, Pleciobates pacholatkoi, Ptilomera burmana, Rhyacobates anderseni, Ventidus pulai) are new records for China. In addition, Nine new species (Timasius yunanensis, Ranatra lansburyi, R. sterea, Micronecta (Micronecta) erythra, M. (M.) janssoni, M. (M.) lobata, M. (M.) ornitheia, M. (Unguinecta) melanochroa, Anisops pseudostali) based on material collected during this study, have been described and published elsewhere.