Wetlands are natural complex ecosystem which formed by the interaction of terrestrial and aquatic systems. Due to wetlands have many ecological functions (e.g. water storage, regional climate regulation, air purification), they play an important role in maintaining regional ecological security and ecological balance. With the increasing impact of global climate change and high-intensity human activities, the environment of the wetlands received serious destruction and faced with the decreasing of water levels, pollution of water quality, destruction of habitats, reducing of biodiversity and so on. In order to restore degraded wetland, ecological conditions (e.g. vegetation, water level, the quality of water) in the period when wetlands are not affected by human activities should be selected as reference conditions for wetland restoration. Therefore, it is particularly important to reconstruct the wetland environmental characteristics that are not affected by human activities. Diatoms, taxa of plankton, are widely distributed in ocean and freshwater systems. Diatoms are primary producers in the aquatic ecosystem and act as essential parts of the food chain. Due to the siliceous cell walls of diatoms, the dead diatom shell is not decomposed and deposits in the sediment for a long time. Diatoms are widely used to monitor modern environments and reconstruct paleoenvironmental conditions because of the special characteristics of diatoms. Such as diatoms are widely distributed in humid environments, different diatom species indicate different environmental information, the frustule of diatoms are well stored in sediments, and valves of different genus diatoms are easy to identify. The application of diatom as a biological indicator has been extensively studied in aquatic ecosystem in China, but most of researchers now focus on lake ecosystems. Since wetlands are formed by the interaction of terrestrial ecosystems and aquatic ecosystems, diatoms can also be used as one of the indicators for monitoring changes of wetland environmental factors and reconstructing the paleoenvironment of wetlands. Although some studies have focused on wetland diatom research, systematic research is still inefficient. The potential environmental significance of diatoms in wetlands is not fully understood. In this paper, diatom researches in the wetlands around the world are summarized and compare with related works of diatoms in other aquatic ecosystems. The current results of diatom research in wetland are reviewed and several suggestions on how to improve diatom research in wetlands in the future are also proposed. It is hoped that our research results will be helpful to the study of diatoms in wetlands in the future.