Wetland ecosystems are critical habitats for various types of wild lives and are important com-ponents of global ecosystem. However, with climate change and human activities, wetlands are facing with degradation. Surface water and groundwater (SW-GW) interactions play an essential role in matter and en-ergy cycling in wetlands, and therefore affect the evolution and health of wetlands. But the role of groundwa-ter in wetland ecosystems has been neglected or simplified. In this paper, we reviewed how surface water interacts with groundwater, and made a systematic summarization of the role of SW-GW interactions (such as maintaining water balance and biological diversity and removing pollution) in wetland ecological functions. We also reviewed the methods to investigate, simulate and quantify SW-GW interactions and related reac-tions. Finally, we illustrated how climate change and human activities affect SW-GW interactions and there-fore affect wetland functions. We highlight the importance of groundwater in wetlands and the urgency to intensify the research in integrated multidisciplinary monitoring and simulation methods, dominant varia-bles and thresholds and integrated water resources management of SW-GW interactions, and further aim to stimulate better protection and restoration of wetlands all over the world.