Recently, the services of wetland ecosystems have attracted increasing attention from resource managers, researchers, and the wider public. This closer focus is partly because of the growing recognition of the ecological services that wetland environments provide, including various resources for different beneficiaries, as well as habitats and refugial biotopes for different wetland organisms. Moreover, wetlands located along bird migratory routes, such as the large tidal flats of the Chinese coastal wetlands, supply food for millions of birds traveling across East Asia and Australia. Thus, wetlands are not only important for human survival, particularly to those relying on local fish, but also for the survival of millions of migratory birds and other organisms. According to the Millennium Ecosystem Assessment (also called MA), the wetland ecosystem services are classified as provisioning, regulating, supporting, and culture. The services available from wetland ecosystems depend on a number of related ecological structures and processes on different temporal or spatial scales. The size and extent of the human benefits from the wetland ecosystems have close relationships with the temporal and spatial scales of the ecological systems. However, the original beneficiary and the ultimate beneficiary of wetlands often existing different spatial scales. Thus, the "spatial difference" exists between the ecosystem services provided by the wetlands and the services received as an end product. Currently, based on market prices, the shadow project method, and the replacement cost method, typical mature wetland ecosystems and their services have been evaluated as case studies. Some studies have also been based on direct extrapolation through the value per unit area for the analysis of services at larger spatial scales, such as for a province or river basin. However, no research has been undertaken for the non-destructive evaluation and control of spatial structures. Thus, the scale of transformation in wetland ecosystems and the respective evaluation of their services have been both a hotspot and an obstacle for wetland ecology studies. Research on spatial-scale transformations in wetland ecosystems evaluation mainly involves three aspects:(1) a clear definition of the ecological spatial-scale transformation; (2) an analysis of the regular differences between spatial scales; and (3) the technologies and methods of space-scale transformation evaluation. In this paper, based on the analysis of the characteristics and regular differences between spatial scales of wetland ecosystem services, we first discuss the concept of spatial-scale transformations in wetland ecosystem service evaluations, which is considered as the value of another similar ecosystem (with more space or less space range) being evaluated to estimate the value of the other wetland ecosystem. Second, we present the commonly used methods of spatial-scale transformation in wetland ecosystem service evaluations (focusing on scaling-up spatial transformations), which mainly include the reference method and the spatial analysis method. The direct extrapolation method and benefit transfer (meta-analysis) method are included in the reference method. Finally, we summarize the problems that existed in the present study:(1) difficulties in applying the reference method directly to calculate the value of wetlands; (2) precision issues in the original data used for studying the scale of transformation; (3) parameter problems in the model used for studying the scale of transformation; (4) lack of research on the measurement and characterization of the scale of transformation; (5) and uncertainty in the analysis of the scale of transformation. Furthermore, we also discuss different perspectives for future research on the scale of transformation and evaluation of wetland ecosystem services.